Here are a few card suggestions to add to the celestial time keeper rats' gear:
Countdown The next player will have limited time (tbd) for completing his turn. If playing a multiplayer game with already limited time, this is halved. If against the AI the number of iterations gets limited.
In addition a large blinking semi-transparent countdown overlays the screen, to add to that player's stress!
Warping the very fabric The next player will be able to complete his turn as usual, but once he's done all is reset to when his turn began. Then the exact same actions are played again
in a random order (some may become invalid).
Set in stone Disable the undo button for the next player's turn (edited) Instead the next attempt to use the undo button will be rejected. Indeed this spell is only fun/useful if the opponent tries to undo a blunder. If this doesn't happen in the next turn, let's wait until the game finishes. Also we'd have to think about a way to somehow replicate this effect on the AI