Okay, actually, I kind of like the following plan, but obviously both hyramgraff and liopoil would need to be on board for it:
hyram controls 5 right, I control A up.
hyram looks in A5 (currently A1), and liopoil moves into whichever of D5 and E4 is "safe".
I think this requires minimal trust, and gets good use out of our turns.
If hyram doesn't move 5 right, then liopoil can move to the vision chamber.
If I don't move A up, hyram wastes an action.
If hyram doesn't look in A5, he could move into my space, and then I act before him and besides I'd be surrounded by empty/safe rooms.
liopoil is forced to move into D5 or E4 which could be trapped/acid bath.
liopoil goes first next round, so he can move into the vision chamber then.
Let's see, analyzing the situation where I'm a guard...
if I didn't move A up, I'd have 2 actions that I could use to mess things up...
If E4 is an acid bath, AND I control 4 left, I could move into the acid bath and kill liopoil.
So, if E4 is an acid bath, hyramgraff should not go through with this. Otherwise though, I think it would work.
What's nice about this is, if hyram's a guard we reveal room E4 which might be an unannounced Room 25 (that would mean he wouldn't go along with it though).
If liopoil's a guard we might be forcing him to reveal C5, since E4 could be the mortal chamber.
Otherwise, this is essentially the same as hyram moving into the vision chamber and looking at A1.