can you just plane shift a tarrasque away?

[FabulousFizban]

seems like the easiest way to get rid of the damn thing. who cares if it can regenerate if you send it to the plane of mayonnaise

[Slipperychicken]

It may take a lot of casting, since it has 25 AC, +9 on charisma saves, advantage against spell saving throws, and legendary resistance 3/day.

Also it no longer auto-regenerates to be unkillable. So standard methods will simply put it down for good.

You need a tuning-fork-thing attuned to the relevant plane, which isn't a given. There may also be issues with how your campaign's cosmology works. It may well be the case that your only real options are to send it to places that you also don't want it to go, like an afterlife area.

[JNAProductions]

I believe there's fluff indicating it's inextricably bound to the material plane.

[Kane0]

I believe there's fluff indicating it's inextricably bound to the material plane.

My personal headcanon is there is one big T or its equivalent per plane; if you were to somehow shift one elsewhere it would be like a swap.

[firelistener]

It is indeed technically possible. Not easy, and probably not even the "easiest" solution, but possible.

Let's assume a 5e level 20 wizard. The tarrasque has an AC of 25, advantage on all saving throws against spells, and has 3 legendary resistances per day (legendary resistance allows it to choose to arbitrarily succeed on any failed save).

Plane Shift, when cast on an unwilling creature, requires a melee spell attack hit followed by a charisma saving throw.

The wizard has a proficiency bonus of 6 and intelligence modifier of 5, so our hero gets +11 to the d20 roll of the melee spell attack attempting to beat the tarrasque's AC of 25. That means there is a 35% chance that the spell attack lands. Then, the tarrasque has a +9 to charisma saves with advantage against our wizard's spell DC of 19 (8+6+5), so it needs to roll lower than 10 for the spell to succed. Since it has advantage, this yields a 20.2% chance the tarrasque fails. Combined, we arrive at a 7.07% the spell hits and succeeds, allowing our wizard to choose another plane for the tarrasque to terrorize.

Our wizard has, at most, 4 chances to cast this spell. The probability of our wizard failing an individual cast is 92.93%. Failing four times in a row comes in at about 74.58%. The complement of that yields the probability that we succeed at least once somewhere in those 4 casts, so 25.42%.

So assuming we have already burned through the tarrasque's legendary resistances and just cast Plane Shift every turn, we have about a 1 in 4 chance of sending our foe to the plane of mayonnaise.

This, of course, also assumes we can successfully weather the tarrasque's 5 melee attacks per round dealing about that will in total deal about 124 average damage per turn on all successful hits, it's Frightful Presence ability with a DC17 Wisdom save against fear, and its 3 legendary actions per turn that allow it to move and/or take extra attacks.

It's a pretty basic scenario modeled above with plenty of room for optimization and alternatives. (Also anyone feel free to double-check my math lol)

[Son of A Lich!]

Eh... I prefer Maze myself.

Beat a DC 20 intelligence check there, buddy (with your penalty to Int). Meanwhile, I'm going to make myself a nice cup of tea and maintain concentration while we evacuate everyone and myself and few high level wizards will take shifts until we can break you with one onslaught of a coordinated attack.

[FabulousFizban]

Eh... I prefer Maze myself.

Beat a DC 20 intelligence check there, buddy (with your penalty to Int). Meanwhile, I'm going to make myself a nice cup of tea and maintain concentration while we evacuate everyone and myself and few high level wizards will take shifts until we can break you with one onslaught of a coordinated attack.

maaaze!
solid. hadn't occurred to me

[King of Nowhere]

Are we specifically talking of 5e? Because in 3.5 it's quite doable

[Zhorn]

seems like the easiest way to get rid of the damn thing. who cares if it can regenerate if you send it to the plane of mayonnaise

Eh... I prefer Maze myself.

Beat a DC 20 intelligence check there, buddy (with your penalty to Int). Meanwhile, I'm going to make myself a nice cup of tea and maintain concentration while we evacuate everyone and myself and few high level wizards will take shifts until we can break you with one onslaught of a coordinated attack.

It's a solid choice, but you have to give up the plane of mayonnaise in favour of the demiplane of corn instead

[Guizonde]

how to kill a tarrasque? with a large hammer, and a dm that hasn't got the survival instinct of a lemming.

what? a 4th wall kill still warrants xp.

[Mr Beer]

My personal headcanon is there is one big T or its equivalent per plane; if you were to somehow shift one elsewhere it would be like a swap.

So we swap it out for Mayonnaise Tarrasque? That's so much worse.

[Psyren]

Are we specifically talking of 5e? Because in 3.5 it's quite doable

This; definitely need an edition here.