Shalimar, the Darkstalker

Prowl {2}{u}{b} (You may cast this for its prowl cost if you dealt combat damage to a player this turn with a Rogue.)
Whenever Shalimar, the Darkstalker enters the battlefield, tap up to X target creatures, where X is the amount of Rogues you control. If Shalimar, the Darkstalker's prowl cost was paid, instead destroy those creatures.
"Meow!"