Bog Goblins

Swampwalk
{t}: Bog Goblins deals X damage to target creature and X damage to you, where X is the number of untapped Swamps you control.
Banished years ago from their mountain home, the goblins of Id'ra Mur have adapted well to life amidst the wretched bog, adopting quite naturally the ruthless self-preservation tactics of the bog's most reprehensible denizens.