Tendrils of Corruption

Instant, 3B (4)
Tendrils of Corruption deals X damage to target creature and you gain X life, where X is the number of Swamps you control.
Darkness doesn't always send its minions to do its dirty work.
Illus. Vance Kovacs

Gatherer Card Rulings [Nov 2009]

• 10/1/2009: The amount of life you gain is equal to the number of Swamps you control, not the amount of damage Tendrils of Corruption deals (in case some of it is prevented).
• 10/1/2009: If the targeted creature is an illegal target by the time Tendrils of Corruption would resolve, the entire spell is countered. You won't gain any life.

Format Legality	Legal in Vintage, Legacy, Extended, Standard, MTGO Classic
Printings (3/19)	Duel Decks: Garruk vs. Liliana (Common) Magic 2010 (Common) Time Spiral (Common)