World Breaker
Oracle Text
Devoid (This card has no color.)
When you cast this spell, exile target artifact, enchantment, or land.
Reach
, Sacrifice a land: Return World Breaker from your graveyard to your hand. ( represents colorless mana.)
Card Rulings
1/22/2016 You can activate the last ability only if World Breaker is in your graveyard.
Here's the card advantage, broken down: You cast World Breaker, (-1 hand adv.), exiling one of their cards (-1 opp. field adv., possibly setting them back a turn land-wise). They remove it (-1 opp hand adv.). You activate its ability (+1 hand adv., -1 field adv.). The cycle repeats. That's totals up to a net gain in the number of cards you have over your opponent, so removing it is futile for your opponent. If they leave it there, a 5/7 with reach can block or be blocked by a lot of things and survive. It's an incredibly well-designed card.