I haven’t tried it myself, but I’ve seen the potion keeper thing awhile back. On Potion Keeper there’s at least one sweet spot at the overlapping edge of the center AOE and the right-side AoE. Standing there will cause neither AoE to kill the player. Of course the big center-of-the-room aoe still kills the player if they don’t move.
I haven’t dared try it myself, since I don’t want to die, but I could try finding it with unbending or something.
The opposite side of the coin, I’ve been killed by the worm world boss while very, very, very clearly outside of the AoE by like an arms-length. I wasn’t exiting the AoE either, I was already outside of it and safe… #rage.
I’ve heard speculation that a player’s hit box is somehow tied to the size of their play-space. You would know best I assume. That is, a smaller playspace = a smaller hitbox, vice-versa. Not sure if that’s true.
(Riley’s answer below:)