When you set this scheme in motion, destroy target creature an opponent controls. If a creature is destroyed this way, you gain life equal to its toughness.
Printings
From
$2.88
Buy
Rulings
13 Jun 2017
If the target creature isn’t destroyed, most likely because it has indestructible, you won’t gain any life. The same is true if the target creature leaves the battlefield before this scheme’s triggered ability resolves.