Dealing damage in increments of two was seen as leading to a desirable pace of play
The card must be able to be built-around in multiple ways in the format (sorry The Rack, Scapeshift, and Ad Nauseam, you don't count.) At least one deck that uses the card must be Modern viable at the time of this publication Now with only ten spots to use, I know I'll inevitably leave out some favourites, so please don't be shy in the comments with some honorable mentions
If a creature enchanted with an Aura that has umbra armor has indestructible, lethal damage and effects that try to destroy it simply have no effect
It's a one-sided stax piece, so the controller has no restrictions while everyone else is locked out of casting the star of their deck
As with all Universes Beyond cards, nobodys sure when or if Wizards of the Coast will ever reprint Arwen, Mortal Queen (with or without its original name and flavor), so its especially sensitive to this kind of spike in demand
This Arabian Nights sorcery forces players to pause their current game and play an entirely new subgame of Magic