So, you create a card. Let's call it, Mega Rock. You're sick of your friends "repurposing" everything you play, so you decide to make it impossible to discard, steal, move, destroy, etc. You balance it out with a piddling point value, but you want that thing to stay put. So it does.
Then that Act of God card somebody made a few games back tries zapping your card into oblivion. No damage, right? Well... Act of God cannot be negated, countered, stopped, delayed, or ignored. So, what now?
Well, it depends.
The Irresistible Force Paradox is an ancient logic puzzle, that thankfully can never come up in real life. (There is no such thing as an irresistible force nor an immovable object). However, paradoxes and logic faults come up incredibly frequently in 1000 Blank White Cards. This particular paradox is the extreme, but smaller contradictions abound.
Therefore, it's up to the house rules to solve this one. Does the newest card not take effect? Should both be discarded? Should the player be forced to take his turn back? Or does it tear at the very fabric of the game, removing all pools and hands from play?