I like the idea for the card, but then I look at the physical aspect of it. We are ordering our creatures to slam/ram/charge hard physical objects. Picture poor Mr. Shrodinger's Cat flung into a tower, Cat-a-Pult style. There should be some chance the creature dies, based on HP of said creature. Bigger the creature, better chance it has to live through the round. So let's talk percentages...The largest actual, playable, creature cards in the game are upped Armagio and upped Colossal dragon, if memory serves me, and they both have 30 health. Just tossing numbers around, maybe a 4% chance to survive impact per current health point of each individual creature. So that way, the game's 2 toughest creatures will always live, and the horde of graveyard skellies have a very small chance to survive. Makes sense to me...
OR,
Simply assign random damage to each monster colliding with an object, maybe, I dunno, 0-5 damage, which gives even the weenies a lucky shot to survive, and the tougher ones would still most likely be hurt.