What spells should the DM give session zero advice on?

[Darth Credence]

Don't know if that title makes sense or not. Based on some other threads, such as the one on suggestion and EBT, I have decided that it would be a good idea to write up a document to give to casters detailing how I would rule on various spells. What I'm hoping for, here, are suggestions for what spells should be on that list. For example, clearly suggestion should be - I would plan on having suggestion listed with what my thought process would be and a few examples of what I would rule. On the other hand, I can't see spending the time doing this for magic missile - the RAW seems to be clear enough that it doesn't need an advance guide.
Any spells anyone can think of that they wished they knew what the DM would rule before they decided to take that spell? Should I expand this beyond spells to other abilities, like smite and whether I would rule it ok for unarmed strikes? Thanks in advance for any ideas here.

[NecessaryWeevil]

Anything involving illusions and charm effects, would be my immediate answer. Maybe ask if they intend to rely heavily on any spells in particular.

[MoiMagnus]

Illusion spells.
1) Someone might think they are light tricks. They are not per RAW. (Real light tricks would still be opaque once you know they are a light trick, not suddenly become transparent). Illusion is mostly a mental effect that trick people's mind, not their eyes.
2) Does it automatically fools someone that doesn't take an action to investigate (unless direct interaction)? For example, if I use silent image to summon an illusionary wall in front of me, does the illusion include the mental effect of convincing that it is reasonable that a wall has appeared in front of me, or does a clever enemy will understand that I don't have the level to actually summon a wall so that it's most likely an illusion (without needing to make an investigation check).

Counterspell.
What do you know of the spell before choosing to counterspell or not? Do you know the spell? Just it's level? Do you know it's target? A rough direction in which the spell is being cast?

Magic Weapon.
If magic items will be so scarce in your campaign that this spell might be the only way for martials to effectively harm creatures resistant to non-magical damages, it is relevant to signal it.

Additionally
If you're playing high level, a discussion on Legendary Resistance is also appreciable.

[Gtdead]

Not just spells. Some are more obvious than others and some of them have already been answered by sage advice, but these are from the top of my head. May add more when I remember them.

- The Conjure line of spells and minionmancy in general.
- Magic Missiles interaction with +MOD to damage.
- Cleric's Divine Intervention options.
- World reaction to undead minions.
- Spirit Guardian's damage on caster's turn.
- How Surprise and hiding in combat is going to work.
- Polymorph choice of beasts (or more commonly if T-Rexes exist in the world)
- His opinion about divination spells like Commune and Contact other Plane
- Illusions. Cover creation and enemy interaction with Mirage Arcane's possible terrains like lava.
- Reliable talent and Glibness. Also skill DCs in general and what "impossible" means for the DM (as per the DC 30 description).

[king_steve]

I think one thing to mention is how you plan on handling spell components including:


free hands for S and SM spells
acquiring new components
tracking material components with gold values, for example Chromatic Orb needs a diamond worth 50g.
tracking material components that are consumed


Some tables hand wave some of these rules and other's can be more strict about free hands.

I would also call out how you plan to handle Wizards (or anyone with the Ritual Caster feat or Tomelocks with the Book of Ancient Secrets) acquiring new spells as they adventure. The cost per spell level and the time needed to write spells into their books can be cumbersome, depending on the pace of the adventure and the amount of gold the players acquire.

[JackPhoenix]

1) Someone might think they are light tricks. They are not per RAW. (Real light tricks would still be opaque once you know they are a light trick, not suddenly become transparent). Illusion is mostly a mental effect that trick people's mind, not their eyes.

Good thing they are FICTIONAL light tricks that DO suddenly become transparent when you know it's a trick. You know, because it's magic instead of a real world physics. They absolutely aren't in people's mind per RAW (Phantom Force being a notable exception)

[Darth Credence]

This is all good stuff - thanks everyone. Some I have already covered with my players, and some I hadn't thought about at all. Charm and illusions seem to be the biggest categories - I'll probably start by going through all spells in the illusion or divination schools, then focus on the enchantments. More thoughts are always appreciated!

A few follow up questions on some of these.
For legendary resistances, what are you thinking should be discussed? The only thing I am coming up with is whether or not I will straight up tell the players that it used a legendary resistance slot. Is there something else to discuss there?
For reliable talent and glibness, I'm not sure what the discussion would be. They both seem pretty clear based on RAW. Is it just about how DCs are set up?
I assume the discussion about divine intervention would entail how a given deity would intervene, correct?

[Gtdead]

1) For reliable talent and glibness, I'm not sure what the discussion would be. They both seem pretty clear based on RAW. Is it just about how DCs are set up?
2) I assume the discussion about divine intervention would entail how a given deity would intervene, correct?

1) A simple question to ask is that, since the DC for impossible is 30, how would he deal with a Bard that can beat it without even rolling. Also what does "impossible" means in the context that the books describe. Is it "make the bbeg commit suicide" impossible, or more like "give me all your money" impossible. Even if you don't get a clear answer, these 2 abilities are a nightmare to deal with, especially for an inexperienced DM or someone that comes from a previous edition. So it's good for him to be aware of them.
2) Yes, a framework for the player to know what to expect. Is it ok for the player to ask for a specific spell for example, like Wish allows, or he just asks for help with his situation and the god decides how to best help, which is completely out of control of the player. Or something in between.

[nickl_2000]

How will you run summons and minionmancy.

[sithlordnergal]

Illusions: This one has been called out already, but a very notable example is Phantasmal Force. The example given in PF is very similar to the example given in Suggestion, in that its not very helpful and makes that spell exceptionally strong. Like...literally, the example has a guy fall through an illusionary bridge, and instead of disbelieving the illusion they think a wind blew them off. You'll need to make sure the players know when a creature gets to make the Int Check to disbelieve the illusion.


Conjuration: You're going to want to hammer this one out too. Are you going to limit how many creatures a player summons? Will you choose the summons, or will the player? Will you control the creatures? Do the creatures act independently, with their own individual initiatives or will you use a group initiative? What kind of creatures can you reasonably expect to be able to summon?

Polymorph/True Polymorph: Similar to Conjuration spells, what kind of beasts can you turn into with Polymorph? Does Polymorph/True Polymorph count as having seen a creature for abilities such as Wild Shape and/or Shapechange?

Simulacrum: Can your Simulacrum make a Simulacrum?


In a similar vein of thinking, you might also want to go over some details with Wild Shape, specifically what can the Druid wield while Wild Shaped? Not only that, but can a Moon Druid's Elemental forms wield weapons and wear armor? What sort of magical gear can a Druid use while Wild Shaped? Or do they just keep the effects of their gear even if its melded into them? We technically have stat blocks of Elemental Myrmidons, which are basically Elementals that wear armor and wield weapons, so its more than possible for an Elemental to do both of those things.

[sayaijin]

1) A simple question to ask is that, since the DC for impossible is 30, how would he deal with a Bard that can beat it without even rolling. Also what does "impossible" means in the context that the books describe. Is it "make the bbeg commit suicide" impossible, or more like "give me all your money" impossible. Even if you don't get a clear answer, these 2 abilities are a nightmare to deal with, especially for an inexperienced DM or someone that comes from a previous edition. So it's good for him to be aware of them.


I will second this and state that since the DMG gives a lot of freedom in making skill checks, it might be worth talking to your group about different values at different difficulties. You don't have to get to the point where they know exactly what numerical value they have to beat for a "hard" or "easy" check, but basic ideas of what to expect reasonably.

[MaxWilson]

Don't know if that title makes sense or not. Based on some other threads, such as the one on suggestion and EBT, I have decided that it would be a good idea to write up a document to give to casters detailing how I would rule on various spells. What I'm hoping for, here, are suggestions for what spells should be on that list. For example, clearly suggestion should be - I would plan on having suggestion listed with what my thought process would be and a few examples of what I would rule. On the other hand, I can't see spending the time doing this for magic missile - the RAW seems to be clear enough that it doesn't need an advance guide.

Actually the RAW on Magic Missile are controversial enough that probably do want to spell out this interaction, especially for Evokers: is it N x (1d4+1+[bonuses including INT]), or is it Nd4+N+[bonuses including INT]?

Might want to spell out any restrictions on Polymorph, e.g. do you have to have seen the creature? Do you have to at least know the creature exists? What happens if I Polymorph someone into a CR 5 Gargantuan Chipmunk? Will the DM make up stats for an enormous chipmunk, or does the spell simply fail? Can I milk poisons from a Polymorphed Giant Cobra, and what happens to those poisons when the spell ends?

You definitely want to clarify how you're running Simulacrum because by the book it is the single most broken spell in the game. So I guess what I mean is that you should nerf Simulacrum, and you should let players know up front how you will nerf it and if you are giving it any corresponding buffs. I allow it to duplicate any creature, not just humanoids, and it's allowed to regain spell slots, BUT it's only at 40-65% power relative to the original (random determination) and it has none of the original's non-procedural knowledge, e.g. doesn't know passwords or people's names or the original's future plans.

Might also want to clarify whether Wish can be used to create upcast spells, e.g. can I Wish for Planar Binding VIII (8th level Planar Binding) or only for Planar Binding (at its default level, 5th)?

Might want to clarify whether it's possible to cast the first 9 rounds of Symbol while walking around, then move somewhere (or be Teleported by a buddy) and finish the Symbol on the final round. It gets a LOT more tactically powerful if you can do this.

Might want to clarify whether you're going to allow True Polymorph to mimic specific people and/or types of people (e.g. King Leopold, or a CR 12 Archmage), or if you interpret "kind of creature" to mean "species" only. It's also worth specifying how you're going to rule dropping to zero HP after the "permanent until dispelled" clause kicks in--do you need a Dispel Magic to turn back from an Adult Silver Shadow Dragon into a human being, or can you just claw yourself down to zero HP?

You'll want to clarify interactions between Glyph of Warding and extradimensional spaces like Bags of Holding. If you move the bag 20', does the "if the object is moved more than 10 feet from where you cast this spell, the glyph is broken and the spell ends" clause trigger or not?

[Pex]

Niche, for Sorcerers with Twin spell it's very important what counts as a single target. Is Twin Dragon Breath legal? Yes because the recipient is one creature, no because the damage affects multiple creatures. Is Twin Hex/Hunter's Mark legal, such as multiclassing? Yes because the initial target is one creature, no because the target can change despite not happening at the time of casting.

If a spell can have multiple effects, when Twinned must both targets have the same effect or can they be different? For example, Twin Enhance Ability - must both have Bull's Strength or can one have Bull's Strength and the other Owl's Wisdom? Twin Polymorph - must both be Giant Apes or can one be a Giant Ape and another a Rabbit?

Add in Twin Wish for more confusion.

[Xetheral]

For AoEs that spread around corners like Fireball you should clarify whether "spreading around corners" results in a pattern like Diagram 1 (where a fireball detonated at point P hits character C) or like Diagram 2 (where a fireball detonated at point P does not hit character C).

https://i.ibb.co/GvtVx14/Diagram-1.jpg

https://i.ibb.co/rMrJpKd/Diagram-2.jpg

Speaking of Fireball you should also clarify whether you let the spell deal damage to objects (thus potentially destroying barriers impeding the spread of the AoE, letting it spread farther) or whether you rule that Fireball can only damage creatures and merely ignites objects (which lets even a paper wall stop Fireball's spread, since the ignited paper won't take damage immediately).

[JackPhoenix]

1) A simple question to ask is that, since the DC for impossible is 30, how would he deal with a Bard that can beat it without even rolling. Also what does "impossible" means in the context that the books describe. Is it "make the bbeg commit suicide" impossible, or more like "give me all your money" impossible. Even if you don't get a clear answer, these 2 abilities are a nightmare to deal with, especially for an inexperienced DM or someone that comes from a previous edition. So it's good for him to be aware of them.

DC for "Impossible" isn't 30. DC for "Impossible" is N/A, because by definition, you can't succeed, no matter what you roll, so you don't even have to bother rolling.

[Hael]

How he treats feedback loops. For instance if a party brings a lot of summons, are you going to keep the encounter as is, or will you alter the number of enemies to compensate. Related is how much the bad guys are expected to change their own battlefield tactics in the face of multiple bad defeats. So for instance inventing an on the fly monster with an aura or aoe to counter the annoying stealthed summoner who’s summons are dominating encounters.

The problem with these feedback loops is that it leads to some absurdities, like how it might be in a players interest NOT to play perfectly, so as to not trigger a DMs response.

[Gtdead]

DC for "Impossible" isn't 30. DC for "Impossible" is N/A, because by definition, you can't succeed, no matter what you roll, so you don't even have to bother rolling.

No need to analyze this, I know what impossible means, and we can have hours of theoretical conversation about the nature of impossibility, preferable with some whiskey. There is a specific rule. It's good form to ask the DM how he interprets the rule.

[JackPhoenix]

No need to analyze this, I know what impossible means, and we can have hours of theoretical conversation about the nature of impossibility, preferable with some whiskey. There is a specific rule. It's good form to ask the DM how he interprets the rule.

Sure, specific rule is that there's no DC for impossible. DC for "nearly impossible" is 30.

[MrCharlie]

Sure, specific rule is that there's no DC for impossible. DC for "nearly impossible" is 30.
Most generally, the specific rule is that the DM sets the DC.

Anyone trying to "win" the game via making some arbitrary DC should be ignored. The only difficulty for new DM's is knowing when to laugh someone like that out the room.

But otherwise, illusions and charms. Charms in general should be a full table conversation as many players dislike them being used on the party. Similar conversations regarding using stuff like Magic Jar on party members, and using such spells on the party in general. Illusions are relatively clear in general and rely on the player to get around their stated impermeability, but there are a few things experienced DMs might have house-rules and opinions on, like creating illusions of light to see, if an illusion (or a specific one) is see through when the DC is beaten or not, and a whole list of stuff with the illusionist illusory reality ability.

How they'll handle conjuration spells-in particular if they will be using RAW initiative, how they will be deciding what you get when you summon (answers range from "You decide" to "Just tell me you're casting the spell and what option"), and whom controls the monsters when summoned.

I'd also have a conversation about fabricate, particularly if you were planning on using it for any specific purpose (like crafting full plate at half price, which RAW you should be able to do with smith's tools), and in general how the DM imagines the spell working.

Also, find familiar and if he's going to tolerate owls granting advantage constantly, how liable the familiar is to die, stuff like that.

If you want to go even more advanced, stuff like is contingency can be used to gather arbitrary information via true or false questions and binary search, how divination spells will work, whom you are contacting with a few of the more ambiguous divination spells like contact other plane, etc.

[Samayu]

If you choose to send more than one magic missile at the same target, does that target need to roll a save for concentration more than once?

But... do you really need to write this stuff out? I'd say it kinda depends on your players. Are they experienced enough to have expectations about the spells and abilities? If not, don't bother. Just keep an eye on their spell lists, and talk to them when one of the problem spells appears. And make sure you let them recall actions if you have to explain to them that it doesn't work the way they thought.

It might not be necessary to make note of anything except the most problematical. Or at least to share only those. But by all means, make the list, and keep it updated over time.

[BloodSnake'sCha]

How witch bolt work and why it is not a good spell to use.

How sleep work and how not to hit yourself and your party with it(happen in my table. The monk and ranger were Elf and saved the party from a TPK)

[Darth Credence]

It might not be necessary to make note of anything except the most problematical. Or at least to share only those. But by all means, make the list, and keep it updated over time.

I am looking to have a list, not just for the players, but for me so that I can ensure I am consistent about rulings.

This has all been great, and things have been brought up I had never even considered.

[da newt]

how do you:
determine range and AoE in 2D and 3D
flanking
cover
low light, darkness, magic darkness
hard corners
SUGGESTION
Athletics vs Acrobatics
how does the world view other species
what books are allowed
do you count ammo, rations, etc
buy, find, craft magic stuff
metagaming


I've seen variability with all of the above with different DMs.