Easy way to bypass True Seeing?

[JPhil]

I was just curious if anyone sees a flaw in this approach to prevent True Seeing from overcoming a magical disguise:

1. Cast Alter Self, use Hat of Disguise, or other magic/item to disguise yourself
2. Cast invisibility on a mask/hood (like an executioner's hood)
3. Put hood on
4. Success!

Basically my thinking is this: If someone does not have true seeing, they will see through the invisible hood and see your magical disguise, and have no idea you are wearing a hood or are disguised (assuming they pass their check). If they have true seeing, they see things as they really are, meaning that they see that the hood is invisible. But true seeing cannot see through solid objects and so all they see is some weirdo walking around with an executions hood on. If they then dispel true seeing, they just see the magical disguise. Either way, they can't see through the disguise.

Thoughts? And any way to improve this further?

EDIT: And yes, I realize you could just walk around with a normal hood on and avoid all of this, but at least this way the only people that see it are the scarce few with True Seeing active.

[Gruftzwerg]

1. Cast Alter Self, use Hat of Disguise, or other magic/item to disguise yourself
2. Cast invisibility on a mask/hood (like an executioner's hood)
3. Put hood on
4. Success!


What you are trying here is to put a mundane "disguise" over your magical one. For that we have the skill "disguise". So basically you would have a magical disguise (with its own disguise roll) covered by a mundane way to disguise yourself. Imho making the mask/hood invisible would just make you more suspicious. Just go with a mundane way to cover your body and thus your identity.

edit: and multiple magical layers of disguise don't have any other effect on True Seeing than a single layer. TS will penetrate any amount of magical layers. You need a mundane barrier that blocks vision.

[Doctor Despair]

There's literally a spell for this. Cloak of Khyber

[JPhil]

What you are trying here is to put a mundane "disguise" over your magical one. For that we have the skill "disguise". So basically you would have a magical disguise (with its own disguise roll) covered by a mundane way to disguise yourself. Imho making the mask/hood invisible would just make you more suspicious. Just go with a mundane way to cover your body and thus your identity.

But that's not quite the same. If I do a non-magical disguise I get a +2 buff. That's fine, but barely worth it if you want to reliably stay disguised. This way, using alter self I get a +10 disguise check, for example, and every person without true seeing doesn't notice anything is amiss. If someone has true seeing, they will certainly see something weird is going on, but they either see a person with a sack on their head, or they have to roll against a +10 disguise check to see my real identity. And with some other items, like Mask of Lies, I can magically buff my disguise check even further and make it effectively impossible for anyone to see through the disguise.


edit: and multiple magical layers of disguise don't have any other effect on True Seeing than a single layer. TS will penetrate any amount of magical layers. You need a mundane barrier that blocks vision.

True seeing doesn't allow one to see through a solid object that is magically made invisible. The spell says one "sees invisible creatures or objects normally". That is, an invisible hood with true seeing will appear as a non-invisible hood, and so true seeing does not allow one to see the magic underneath the solid hood (further down it says "True seeing, however, does not penetrate solid objects.). It's not about stacking layers of magic. It's about the fact that a solid hood is solid, and stops true seeing, regardless of whether it's invisible or not.

[JPhil]

There's literally a spell for this. Cloak of Khyber

Cool, i hadn't seen that. I'd have to see if my DM would allow this, being from Ebberon and seemingly of dubious origin (I can't really find any official reference to it). Either way, a flour sack is pretty easy to acquire and bypasses the need for a spell/item that provides 6+ hours of continuous disguise. This would work well for continuous deep cover, but might be overkill for walking through a busy market or for a single meeting.

[Fero]

Invisible Spel MM (CS) on Obscuring Snow (Fb).

[Doctor Despair]

Cool, i hadn't seen that. I'd have to see if my DM would allow this, being from Ebberon and seemingly of dubious origin (I can't really find any official reference to it). Either way, a flour sack is pretty easy to acquire and bypasses the need for a spell/item that provides 6+ hours of continuous disguise. This would work well for continuous deep cover, but might be overkill for walking through a busy market or for a single meeting.

It's from City of Stormreach

[JPhil]

Invisible Spel MM (CS) on Obscuring Snow (Fb).

Basically the same effect, albeit with snow in place of a physical mask, no? But requires you to burn a feat...

[Fero]

Basically the same effect, albeit with snow in place of a physical mask, no? But requires you to burn a feat...

True. I guess it depends on your overall goal. I find Incisible Spell by itself, and the above combo to be incredibly useful for dedicated illusionists. However, if you are not focused on illusion and just want a disguise, the combo is less useful.

[FauxKnee]

There are plenty of arguments about it, but I personally ascribe to the belief that mind blank blocks true seeing.

[Darg]

There are plenty of arguments about it, but I personally ascribe to the belief that mind blank blocks true seeing.

I ascribe to Nondetection being the defacto blocker. Mind blank does not say it works on your items/gear. And having a built in failure point keeps Nondetection from being broken. Instead of an arms race, it's the roll of the dice.

[JPhil]

I ascribe to Nondetection being the defacto blocker. Mind blank does not say it works on your items/gear. And having a built in failure point keeps Nondetection from being broken. Instead of an arms race, it's the roll of the dice.

This is my DM's prerogative too. People balk at the idea that a 3d lvl wizard spell could bypass a 6th lvl spell, but if you make it a caster-level check then it really just comes down to who's more powerful, which makes perfect sense, and would explain how powerful wizards can walk around disguised with no real risk of being exposed.

But, for low levels, I still like my sack-over-the-head approach.

[Doctor Despair]

As I said upthread, Cloak of Khyber (CoS) is the simple answer, but I also want to point out that the bigger challenge is Detect Magic (or arcane sight/greater arcane sight) in conjunction with any other detection mode. See "Master of Disguise" in my sig for more info on Disguise challenges and answers.

[Crake]

As I said upthread, Cloak of Khyber (CoS) is the simple answer, but I also want to point out that the bigger challenge is Detect Magic (or arcane sight/greater arcane sight) in conjunction with any other detection mode. See "Master of Disguise" in my sig for more info on Disguise challenges and answers.

There's an solution for that as well, the spell misdirection, which can also be combined wonderfully with nystul's magic aura to quite literally give yourself whatever aura you desire, whether that be with regards to magic, or even alignment.

[Doctor Despair]

There's an solution for that as well, the spell misdirection, which can also be combined wonderfully with nystul's magic aura to quite literally give yourself whatever aura you desire, whether that be with regards to magic, or even alignment.

Nystul's magic aura affects items-- not people. Doesn't stop you from lighting up like a Christmas tree. You can also line your clothes with lead to protect some items like rings.

Misdirection allows a save, so it's not ideal, and can prove problematic for certain disguises. It is an answer. Mind Mask also helps to some extent, but also shoehorns you into a disguise with neutral alignment. Spymaster/Zhentarim Spymaster's Deep Cover are the best answers, but prohibitively expensive.

[icefractal]

To make the hood less obviously a divination-foil, wear full-body armor that includes a face-concealing helmet, and make the helmet invisible. If anyone questions why, you just want your vision unobstructed while keeping the helmet's protection.

[Darg]

This is my DM's prerogative too. People balk at the idea that a 3d lvl wizard spell could bypass a 6th lvl spell, but if you make it a caster-level check then it really just comes down to who's more powerful, which makes perfect sense, and would explain how powerful wizards can walk around disguised with no real risk of being exposed.

But, for low levels, I still like my sack-over-the-head approach.

Yeah, mind blank can have some serious draw backs.

While your idea has merit, it does require a specific reading of true seeing. True seeing doesn't say that it takes away your ability to see magical effects and illusions. I've always envisioned it allowing you a second vision imposed on the the first. Basically they'll know it's a magical disguise.

[Crake]

Nystul's magic aura affects items-- not people. Doesn't stop you from lighting up like a Christmas tree. You can also line your clothes with lead to protect some items like rings.

Right, but you pair Nystul's with Misdirection, since Misdirection makes one creature or object have the same aura as one object, so if you modify an object to have an aura you want, you can then use misdirection to make that creature bear the same aura, which can include nonmagical.


Misdirection allows a save, so it's not ideal, and can prove problematic for certain disguises. It is an answer. Mind Mask also helps to some extent, but also shoehorns you into a disguise with neutral alignment. Spymaster/Zhentarim Spymaster's Deep Cover are the best answers, but prohibitively expensive.

Mind mask would certainly help, but I don't think deep cover would prevent magic from being detected on you, since whether or not a spell is cast on you isn't related to you vs your cover identity.

Misdirection having a save doesn't make it a non-option, nondetection has a fail chance and people were suggesting that too. Not ever defense has to be impenetrable after all, but if you desperately need it to be, then just use irresistible spell from kingdoms of kalamar to make it an 8th level spell with no save.

[rel]

The invisible gimp mask will stop people with true seeing from seeing your face, although they could plausibly identify you via other means (clothes, gait, mannerisms, tattoos / piercings, the specific combo of magic items you like to use, the other party members you always hang around with, etc).

Depending on your GM, it might not work so well on people without true seeing; A creature that interacts with Disguise Self can roll a Will save to recognise it as an illusion.
A lot of GM's will call for the save almost immediately and rule that once the roll to disbelieve has been made, the illusion can be seen through without issue.

[JPhil]

To make the hood less obviously a divination-foil, wear full-body armor that includes a face-concealing helmet, and make the helmet invisible. If anyone questions why, you just want your vision unobstructed while keeping the helmet's protection.

That's a good idea. I was trying to think of normal attire that would shield one's face... this seems like a solid approach.

[JPhil]

The invisible gimp mask will stop people with true seeing from seeing your face

But why not? The mask is solid, and True Seeing doesn't work through solid objects. Perhaps you could argue that they can toggle True Seeing on/off to see invisible objects and see through invisible objects at the same time, but even this wouldn't allow them to see magical effects on the other side of invisible objects. Otherwise the restriction that True Seeing doesn't work through solid objects is meaningless -- just cast invisibility on the solid object and you can now see magical effects on the other side.

So I agree they can see the magical disguise under the mask, but it doesn't make sense that they automatically see through the disguise and see my true self.

[JPhil]

As I said upthread, Cloak of Khyber (CoS) is the simple answer, but I also want to point out that the bigger challenge is Detect Magic (or arcane sight/greater arcane sight) in conjunction with any other detection mode. See "Master of Disguise" in my sig for more info on Disguise challenges and answers.

Wouldn't nondetection be the natural foil to any detect spells? At least it would force a caster level check.

[Jervis]

If I play a character with invisible spell I always have them cast a invisible spell with some visual effect on me that can create a Yo Mamma joke. So if anyone double takes at me I know they have true seeing or see invisibility. It’s never worked, but one day IT WILL!!’

[sleepyphoenixx]

Depending on your GM, it might not work so well on people without true seeing; A creature that interacts with Disguise Self can roll a Will save to recognise it as an illusion.
A lot of GM's will call for the save almost immediately and rule that once the roll to disbelieve has been made, the illusion can be seen through without issue.

The rules are pretty clear that simply seeing an illusion is not enough to trigger a save to disbelieve it.
If you keep your changes limited to your face they'd actually have to touch it or at least study it carefully, which is unlikely to come up unless you've already aroused suspicion in other ways.

Your GM can of course rule otherwise, but "the GM could screw you over with a houserule" applies to pretty much anything.

[Crake]

The rules are pretty clear that simply seeing an illusion is not enough to trigger a save to disbelieve it.
If you keep your changes limited to your face they'd actually have to touch it or at least study it carefully, which is unlikely to come up unless you've already aroused suspicion in other ways.

Your GM can of course rule otherwise, but "the GM could screw you over with a houserule" applies to pretty much anything.

Interacting, according to the illusion and disbelief section in chapter 10 of the phb, also includes "carefully studying", so it isn't limited to physical touch, and could easily apply if you're in a social scene where people would be scrutinizing your character regardless. This is, however, why alter self is undoubtedly the superior option, or minor change shape in some way (level 1 egoist psion web ACF is probably the easiest method), and completely removes the will save from the equation.

[Gruftzwerg]

But that's not quite the same. If I do a non-magical disguise I get a +2 buff. That's fine, but barely worth it if you want to reliably stay disguised. This way, using alter self I get a +10 disguise check, for example, and every person without true seeing doesn't notice anything is amiss. If someone has true seeing, they will certainly see something weird is going on, but they either see a person with a sack on their head, or they have to roll against a +10 disguise check to see my real identity. And with some other items, like Mask of Lies, I can magically buff my disguise check even further and make it effectively impossible for anyone to see through the disguise.



True seeing doesn't allow one to see through a solid object that is magically made invisible. The spell says one "sees invisible creatures or objects normally". That is, an invisible hood with true seeing will appear as a non-invisible hood, and so true seeing does not allow one to see the magic underneath the solid hood (further down it says "True seeing, however, does not penetrate solid objects.). It's not about stacking layers of magic. It's about the fact that a solid hood is solid, and stops true seeing, regardless of whether it's invisible or not.

I think our interpretation of True Seeing differs here.

Imho:

"seeing things as they are" != "can't see illusions at all"

If you have True Seeing and look at an Illusionary Wall, you see it as it is: an "Illusionary Wall" and what is behind it. It's the same as saving against an Illusion. That also helps you to see the Illusion as it really is (twin layered vision: both the illusion and what is behind it).

Finally coming back to you invisible mask/hood. Imho a similar logic applies here. Those who have True Seeing can see the mask/hood and what is behind in the double layered vision. Thus "line of sight" is not blocked for your True Seeing. The "invisibility" effect doesn't help you against true seeing here imho. That is why I suggested to go with a mundane "disguise" (skill) as second layer.

[sleepyphoenixx]

I think our interpretation of True Seeing differs here.

Imho:

"seeing things as they are" != "can't see illusions at all"

If you have True Seeing and look at an Illusionary Wall, you see it as it is: an "Illusionary Wall" and what is behind it. It's the same as saving against an Illusion. That also helps you to see the Illusion as it really is (twin layered vision: both the illusion and what is behind it).

Finally coming back to you invisible mask/hood. Imho a similar logic applies here. Those who have True Seeing can see the mask/hood and what is behind in the double layered vision. Thus "line of sight" is not blocked for your True Seeing. The "invisibility" effect doesn't help you against true seeing here imho. That is why I suggested to go with a mundane "disguise" (skill) as second layer.
This one isn't really a matter of interpretation. Your "logic" is directly contradicted by RAW. Thrice.

You confer on the subject the ability to see all things as they actually are. The subject sees through normal and magical darkness, notices secret doors hidden by magic, sees the exact locations of creatures or objects under blur or displacement effects, sees invisible creatures or objects normally, sees through illusions, and sees the true form of polymorphed, changed, or transmuted things. Further, the subject can focus its vision to see into the Ethereal Plane (but not into extradimensional spaces). The range of true seeing conferred is 120 feet.

True seeing, however, does not penetrate solid objects. It in no way confers X-ray vision or its equivalent. It does not negate concealment, including that caused by fog and the like. True seeing does not help the viewer see through mundane disguises, spot creatures who are simply hiding, or notice secret doors hidden by mundane means. In addition, the spell effects cannot be further enhanced with known magic, so one cannot use true seeing through a crystal ball or in conjunction with clairaudience/clairvoyance.

The "translucent outline" bit also only applies to figments and phantasms. Invisibility is a glamer.


Creatures encountering an illusion usually do not receive saving throws to recognize it as illusory until they study it carefully or interact with it in some fashion.

A successful saving throw against an illusion reveals it to be false, but a figment or phantasm remains as a translucent outline.

A failed saving throw indicates that a character fails to notice something is amiss. A character faced with proof that an illusion isn’t real needs no saving throw. If any viewer successfully disbelieves an illusion and communicates this fact to others, each such viewer gains a saving throw with a +4 bonus.

[Darg]

Interacting, according to the illusion and disbelief section in chapter 10 of the phb, also includes "carefully studying", so it isn't limited to physical touch, and could easily apply if you're in a social scene where people would be scrutinizing your character regardless. This is, however, why alter self is undoubtedly the superior option, or minor change shape in some way (level 1 egoist psion web ACF is probably the easiest method), and completely removes the will save from the equation.

I don't think it's so easy. It says "stopped and studied" in the example. Combined with "study it carefully" I can't see a situation that someone distracted by what they are doing and the events around them as being "careful" or "stopped." Maybe if they were in an adjacent square or occupying the same space and solely focused on studying the character would that logically be described as having "stopped to study carefully." In social events, most people try to avoid seeming rude so they might study from a distance, but it would be fairly uncommon for someone to walk up to another to start carefully scrutinizing them. I'm just of the opinion that there is simply a difference between normal study/scrutiny vs a "careful" approach.


This one isn't really a matter of interpretation. Your "logic" is directly contradicted by RAW. Thrice.


The "translucent outline" bit also only applies to figments and phantasms. Invisibility is a glamer.

True seeing doesn't say that you can't sense what the magic is telling you. See invisibility allows you to see invisible things normally and goes on to show you that they don't appear normally. That same dichotomy can easily apply to true seeing. It would be really weird if you turned your head and found that the door you were just looking at from 120+ ft away simply disappeared on you as you walked toward it. If you couldn't see the illusion, then the obvious conclusion is that some sort of transmutation happened and you would never know you got duped or some sort of nondetection was cast on it. No longer seeing the illusion causes edge case headaches. Still seeing the illusion causes no headaches and complies with the permissive nature of the rules.

Invisibility doesn't have a saving throw except on the target (unwilling). Glamers that allow saving throws to targets other than the direct target explain what happens when the target succeeds. Disguise self only allows that the target recognizes it as an illusion. Veil on the other hand allows them to see through the glamer; on the plus side, carefully studying the veiled target isn't enough to receive the disbelief saving throw.

[sleepyphoenixx]

True seeing doesn't say that you can't sense what the magic is telling you. See invisibility allows you to see invisible things normally and goes on to show you that they don't appear normally. That same dichotomy can easily apply to true seeing. It would be really weird if you turned your head and found that the door you were just looking at from 120+ ft away simply disappeared on you as you walked toward it. If you couldn't see the illusion, then the obvious conclusion is that some sort of transmutation happened and you would never know you got duped or some sort of nondetection was cast on it. No longer seeing the illusion causes edge case headaches. Still seeing the illusion causes no headaches and complies with the permissive nature of the rules.

Invisibility doesn't have a saving throw except on the target (unwilling). Glamers that allow saving throws to targets other than the direct target explain what happens when the target succeeds. Disguise self only allows that the target recognizes it as an illusion. Veil on the other hand allows them to see through the glamer; on the plus side, carefully studying the veiled target isn't enough to receive the disbelief saving throw.
What does that have to do with True Seeing not allowing you to see through solid objects?

You're also applying functionality to True Seeing it doesn't have. If it worked like See Invisibility it would say "this works like See Invisibility, but...". It doesn't. It says "you see all things as they actually are".
The spell is powerful enough, it doesn't need a buff that there is no RAW basis for.

[Darg]

What does that have to do with True Seeing not allowing you to see through solid objects?

You're also applying functionality to True Seeing it doesn't have. If it worked like See Invisibility it would say "this works like See Invisibility, but...". It doesn't. It says "you see all things as they actually are".
The spell is powerful enough, it doesn't need a buff that there is no RAW basis for.

Gruftzwerg didn't say you can see through solid objects. They said you can see through them when they are invisible and that true seeing doesn't take away your sense of seeing the object as invisible.

You're the one applying a functionality to true seeing it doesn't have. The rules are permissive. The spell says "you see all things as they actually are" not "you see all things only as they actually are." The text never says it takes away your ability to see things as they actually aren't. So yes, the RAW is strong with this one. And it's only a "buff" when you haven't already been playing this way, and it's not a meaningful power increase when there are plenty of other ways to thwart the ability.

[Thurbane]

A quite expensive, very short term, foil for True Seeing is Dust of Disappearance (bolding mine).


Normal vision can’t see dusted creatures or objects, nor can they be detected by magical means, including see invisibility or invisibility purge.

I used this to try and get the drop on some Erinyes in a certain well known module, but I rolled 3 rounds on my 2d6 round duration :smallfurious:

[JPhil]

Gruftzwerg didn't say you can see through solid objects. They said you can see through them when they are invisible and that true seeing doesn't take away your sense of seeing the object as invisible.

You're the one applying a functionality to true seeing it doesn't have. The rules are permissive. The spell says "you see all things as they actually are" not "you see all things only as they actually are." The text never says it takes away your ability to see things as they actually aren't. So yes, the RAW is strong with this one. And it's only a "buff" when you haven't already been playing this way, and it's not a meaningful power increase when there are plenty of other ways to thwart the ability.


Whether or not true seeing allows you to see through an invisible solid object, the rules are pretty clear that, "True seeing, however, does not penetrate solid objects." That is, RAW are straight forward that True Seeing does not allow one to see magical effects on the other side of a solid (invisible or otherwise) object. So under your reading of the spell, it might be the case that True Seeing still allows one to see through the invisible wall (or mask) and see what's on the other side, but pretty clearly one can't divine any further magical effects on the other side of a real (non illusory) solid object.

EDIT: To add, the spell further states that "in addition, the spell effects cannot be further enhanced with known magic, so one cannot use true seeing through a crystal ball...". This is even more reason why invisibility cannot allow one to see magical effects on the other side of a solid object, as this clearly is using magic to enhance (bypass) the limitations of True seeing.

[Darg]

Whether or not true seeing allows you to see through an invisible solid object, the rules are pretty clear that, "True seeing, however, does not penetrate solid objects." That is, RAW are straight forward that True Seeing does not allow one to see magical effects on the other side of a solid (invisible or otherwise) object. So under your reading of the spell, it might be the case that True Seeing still allows one to see through the invisible wall (or mask) and see what's on the other side, but pretty clearly one can't divine any further magical effects on the other side of a real (non illusory) solid object.

EDIT: To add, the spell further states that "in addition, the spell effects cannot be further enhanced with known magic, so one cannot use true seeing through a crystal ball...". This is even more reason why invisibility cannot allow one to see magical effects on the other side of a solid object, as this clearly is using magic to enhance (bypass) the limitations of True seeing.

No one has said that you'd be able to see using true seeing beyond the solid object; so I think it's likely that everyone agrees on that point.

[Gruftzwerg]

First thank to Darg to explaining my interpretation in my absence. I'm a bit busy the past days and have lil forum time left..


As Darg has said, I'm not arguing about True Seeing giving X-ray vision.
I argue that "seeing things as they are" doesn't mean that you can't see the illusion at all. You are just ware that it is an illusion. And invisible creature/object radiates light in such a way that you can see everything behind it and thus provides you with Line of Sight.
When you now add True Seeing, it doesn't prevent you from seeing what the Illusion provides to your senses. It just adds a second layer where you can see the invisible object. Try to imagine it like having only one augmented reality lense for one eye. You get double layered vision where you are see an illusion at one spot, while still seeing what it behind it.
True Seeing does not eliminate what the illusion implies, it just add the reality to it as 2nd layer.

Finally, have a look at this important part of Sleepyphoenixx's True Seeing quote:


...sees invisible creatures or objects normally, sees through illusions...

Interesting that you stop to bold the text where it starts to contradict your statement. ;)

"See Through Illusions" with no limitation of what type of illusions. Thus any illusion, even those that make you invisible. And no this doesn't contradict the x-ray statement, it imho validates my interpretation of a double layered vision.

[icefractal]

That seems like it would still result in preventing True Seeing from seeing the true face though (edit: see below). Either:
A) You see the invisible helmet as visible; therefore you don't see the face at all.
B) You're aware of the helmet, but you can still see through it (translucent, I guess, in a way that doesn't impede your vision). So you then see ... the illusory face, because True Seeing has no Line of Effect to the second (inner) illusion, and is specifically notes as not penetrating solid objects.

Does this mean that a glass window would block True Seeing? AFAICT - yes. A transparent object is still solid.

Edit: However, while a window would block it, a helmet might not block it from seeing through Disguise Self. Why? Because Disguise Self is on your whole body, not specifically your face, and so since part of it is outside the helmet True Seeing does have LoE. RAI it might make more sense to treat it as based on line of sight to each given point individually (ray tracing style), but we're talking RAW here.

[Darg]

You don't have to have disguise self alter your clothes or dimensions.

Option 2 is correct. The helmet prevents you from seeing the true face behind it with true seeing. This is true regardless of the helmet being invisible or not.

To the edit: it doesn't matter. True seeing is a separate type of vision from your normal vision. Your true seeing vision sees a helmet, your normal vision sees the effect of the disguise self spell.

[sleepyphoenixx]

Interesting that you stop to bold the text where it starts to contradict your statement. ;)

"See Through Illusions" with no limitation of what type of illusions. Thus any illusion, even those that make you invisible. And no this doesn't contradict the x-ray statement, it imho validates my interpretation of a double layered vision.

Does it? Seeing through illusions + invisibility translates to "see the thing as if it wasn't invisible" to me. Or in other words seeing it as it actually is.

I still maintain that there is no RAW support for True Seeing allowing you some form of double vision or giving the ability to choose between normal or true-seeing vision.
It also doesn't need that functionality to work so there is no need to houserule it in.

True Seeing doesn't need to be a strict upgrade to See Invisibility.
Not seeing what you're "supposed" to see - or not even being aware that there is an illusion unless someone points it out - is an acceptable tradeoff for the power to pierce any illusion or magical disguise imo.