Being ready for literally EVERYTHING

[Mrark]

You're a high level group (a high incantatrix, a planar shepherd, a rogue with guns, a dervish, and a cleric), you're pretty good optimized but everything that will break the game is nerfed or negated. You are about to enter the demiplane belonging to the dead god Vecna. Nobody has ever done or even tried something like that, and you have no clue or what you could find. And I literally mean no clue at all: you don't even know if there will be a ground to walk on, air to breathe, you don't know if there will be light or if you will spawn in the middle of a Travis Scott concert. You know nothing.

The question is: What to bring with you?

Given that you have almost unlimited money but your gear is kinda full, what situational item will you bring with you? This includes, but is not limited at consumable items like scrolls, potions, slot-taking items for necessities, and so on. The only limit is what you know exists.

Bring me your shopping carts!!

[TalonOfAnathrax]

The ultimate "ready for anything" build is a spellcaster with lots of actions and spells (Wish to escape anything, Time stop, etc). So what you want is a pile of slotless Belt of Battle items (or one belt with a bunch of slotless Belt of Battle effects added on), plus a pile of pearls of power. Then you use Celerity to activate the best, and you become immune to surprise through Polymorph shenanigans or simply with the Cunning Legacy Item property.

[Biggus]

Given that you have almost unlimited money but your gear is kinda full, what situational item will you bring with you? This includes, but is not limited at consumable items like scrolls, potions, slot-taking items for necessities, and so on. The only limit is what you know exists.

Bring me your shopping carts!!

When you say "your gear is kinda full" does that mean you're not allowed to have new abilities added to existing items?

Either way, Ioun Stones seem like a good start, specifically the ones which allow you to exist indefinitely without food, water and air.

If you've got a high-level Wizard, Druid and Cleric in the party you shouldn't need to buy many items though, they should be able to cover most of the potential problems with spells like Planar Bubble. Just make sure somebody's got an action readied to counterspell with Greater Dispel Magic when you plane shift in there.

As for being prepared for attacks and such, have a look at this list: https://forums.giantitp.com/showthread.php?187851-3-5-Lists-of-Necessary-Magic-Items

[Bohandas]

A ring of three wishes is a good choice for being able to be called on to do whatever.

It would also be good to have some means of canceling out antimagic effects, or else all the magic stuff may not do any good. Some kind of staffmor whatever that can cast Invoke Magic would do. As would a device that creates a Planar Bubvle effect if we're dealing with dead magic planes/areas rather than antimagic fields

Also, it's worth remembering that a lot of rings can't be used simultaneously regardless of whether your ring slots are all full. If you have a Ring of Invisibility and a Ring of the Ram there's no reason not to have a third ring since you can't use the Ring of The Ram at the same time as the Ring of Invisibility anyway

[Telonius]

One Nodwick. Put a Hat of Disguise on him, have him poke his head through the portal first. Pull him back, and see if (1) it's still attached, and (2) if the hat's still working. (Would be just like Vecna to have some horrific trap or Disjunction effect for anybody trying to bother him).

[Morphic tide]

For such a scenario, I'd suggest a Psionic Save Point as the Contingency method, with another party member being a Chameleon cheesed to 8ths or 9ths. Rather than try and deal with everything simultaneously, the goal is to have time shenanigans to acquire foreknowledge for a person with access to Literally Anything to prepare against.

[Rebel7284]

Craft Contingent Spell is fairly useful to have multiple levels of contingencies on everyone. Some of those contingencies can, of course be twinned repeating celerity and such while others get y'all out of danger, be free action miracles, etc.

With that said, you can have all the miracles, celerities, and invoke magics in the world, and the right combination of custom epic spells can still end you especially when the target's portfolio includes knowing all your secrets.

[MaxiDuRaritry]

Along with everyone else's suggestions, try to get [Ex] versions of your magic (and psionic) items via the Create Device feat, from Ravenloft: Legacy of the Blood. Non-magical versions of magic items can't be suppressed in a dead magic zone, and they aren't affected by other stuff that screws over magic items and the ones who use them, such as Ravenloft's Dark Powers™.

A Device-originated acorn of far travel (https://realmofadventure.fandom.com/wiki/Acorn_of_far_travel) from a tree on a plane friendly to the survival of living things (and spellcasters and spells in particular), such as the Astral Plane is important, as well. It's [Ex] so it can't be suppressed, and all durations of effects (including spells and Device effects) on the Astral Plane are suspended. You won't have to eat, sleep, or breathe. The main caveat for that is that you can't refresh spells, although that's why you have a second Device of AoFT in reserve for a fast-time plane that's also friendly to living things to swap out when you need to refresh.

Some protection against the Far Realm and sanity-draining stuff (just in case).

Several Device items, and also locations (etc) that grant bonus feats (https://forums.giantitp.com/showthread.php?400840-List-of-Feat-Granting-Items-Locations-Grafts), as well as a Device item of psychic reformation (https://www.d20srd.org/srd/psionic/powers/psychicReformation.htm) so you can swap those feats out as you need ones for any situation you might stumble into. Better if you've also (not instead) got a friendly psion coming with (who has taken the Supernatural Transformation [Psionics] feat, to buffer against things that might disrupt normal manifesting), so he can manifest psychic reformation using Linked Power for 1 round emergency manifestings.

Devices of psychoactive skin of proteus (https://www.d20srd.org/srd/psionic/items/universalItems.htm#skinofProteus) (of the highest ML possible) for everyone in the party so you have at-will shapeshifting. Being able to adapt your form on-the-fly is important, especially since you gain types, subtypes, and the immunities they grant, as well as any number of [Na] abilities (such as movement modes) they've got. If you can give everyone in the party the Metamorphic Transfer (https://www.d20srd.org/srd/psionic/psionicFeats.htm#metamorphicTransfer) feat, all the better, since that gives everyone access to tons of potential [Su] abilities. (Improved) Assume Supernatural Ability would also be nice, except it's nowhere near as versatile, since you can't change the ability you get on the fly.

A Device of permanent mind blank (https://www.d20srd.org/srd/psionic/items/universalItems.htm#conceal) for everyone! Protects your minds against anything trying to screw with you that way, as well as protects against divinations. Make sure you have mind blank up several months in advance, since Vecna is a VERY high-DvR god of secrets, so he'll be able to learn of your oncoming presence quite a long time in advance (1 week per divine rank). I'm not 100% sure that mind blank protects against divine powers, but at least you can say you've tried.

I dunno if PF is allowed, but a Device iron circlet of guarded souls' (https://www.d20pfsrd.com/magic-items/wondrous-items/h-l/iron-circlet-of-guarded-souls/) abilities should be added to whatever headband slot items you've got. Mind blank to protect your mind, and the circlet to protect your soul.

A Device of protection from evil (https://www.d20srd.org/srd/spells/protectionFromEvil.htm), to defend against possession, and as a secondary defense against mind-control. There's a banner in Heroes of Battle that grants protection from evil to everyone in a radius. Get a separate one for everyone in your party.

A Device necklace of adaptation (https://www.d20srd.org/srd/magicItems/wondrousItems.htm#necklaceofAdaptation), to allow you to breathe and to protect you against a toxic environment, regardless of what it might be.

A Device ring of sustenance (https://www.d20srd.org/srd/magicItems/rings.htm#sustenance), to ensure you can go without food, water, and more than 2 hours of sleep for extended periods, just in case. It also allows the party's spellcasters to refresh spells in 2 hours instead of 8.

Some Device planar ring gates (from the Planar Handbook) and/or some Device-based extradimensional spaces are a definite, just in case resting for spells isn't an option. Popping over to another plane as needed to choose new spells, to purchase or craft items to deal with new situations, to hop out of unexpected dangers so you can prepare for them as needed, and to keep from getting trapped in bad situations are also a must.

Don't forget to add secure interparty long-distance communication abilities to everyone, such as through that feat that grants telepathy, or a few psicrystals.

And a plain adamantine dagger and longsword for everyone, at the very least. The ability to hack through physical objects is very useful. Even more so if they are Device riverine +1 metalline/morphing/sizing/skillful/aptitude weapons (https://forums.giantitp.com/showthread.php?634999-3-P-What-Weapon-Combos-Would-You-Consider-Truly-Legendary), so you can have an extremely versatile multitool at your disposal.

As many thought bottles (from Complete Arcane) as you can afford for the spellcasters in the party. Several days' worth of prepared spell slots come in very handy if you run out. Also, one filled with XP for everyone, so you don't end up energy drained and level 1 in a hostile god's realm. It's also handy for when you need to spend a ton of XP in a hurry, since you're not out of more than 500 in the end. Also, nesting them (https://forums.giantitp.com/showthread.php?217819-Nesting-Thought-Bottles-millions-of-wishes).

And lastly, make sure everyone has various sensory modes. Regular vision, low-light vision, darkvision (including magical darkness), blindsense, blindsight, touchsight (https://www.d20srd.org/srd/psionic/powers/touchsight.htm), etc. For preference, add the Burrowing Power (https://www.d20srd.org/srd/psionic/psionicFeats.htm#burrowingPower) and Transdimensional Power (from Complete Psionic) feats to touchsight, so you can sense through walls, onto other planes, and in extradimensional pockets nearby.

[edit] Oh, and you may want to consider turning your body itself into the items (https://forums.giantitp.com/showthread.php?177889-Brainstorm-for-Psionic-Tricks-Tactics-and-Combos-Handbook&p=23285432&viewfull=1#post23285432), so they can't be taken away from you without flaying you alive. And if they're Devices, they won't even show up as magic.

[remetagross]

Hmm I think I'd go with a scroll of Shapechange for everyone to be turned into a Dire tortoise upon entering the place, so that everyone gets an extra round of actions no matter what (provided no AMF of course). Then there should be an Empowered Quickened Time Stop (from rods or Sudden feats) just in case there has to be emergency actions taken. A scroll of Invoke Magic coupled with a Sanctum Spell'd Plane Shift (so it goes down to a 4th-level spell) should give you an escape button pretty much no matter what can happen.

Also, lots of Reduce Object'd tinfoil hats on everyone to break line of effect from any possible Antimagic fields.

[Melayl]

if you will spawn in the middle of a Travis Scott concert.

I didn't understand how truly evil Vecna was until this moment...

[MaxiDuRaritry]

Take a look at some of the alchemical items (https://forums.giantitp.com/showthread.php?392784-Alchemical-Item-Compendium) out there and start making as many of them as you can, even hiring help (gnomes, say, since they have racial "spellcasting") to make a production line (with lots of Aid Anothers to boost Craft [Alchemy] checks).

Having access to nonmagical alchemical effects can be fantastic, whether it be due to a plane-wide dead magic zone or AMF, or because many outsiders have tons of SR that alchemical items can bypass. Also, there's a lot of utility to be had from easy access to instant fire, cold, or acid on demand. Grabbing a Device that can produce shrink item would allow you to bind a ton of alchemy items together in a tiny bundle you can hurl at your enemies, which will destroy whatever it hits.

[Endarire]

Maxi, Thankee for sharing such a detailed post! It seems like it should be a handbook on how to prepare for anything at high levels!