Berl, Toxin Engineer

Deathtouch
Other creatures you control with deathtouch get +1/+1.
Whenever a creature you control enters the battlefield, you may pay {b}. If you do, it gains deathtouch for the rest of the game.
Whenever a creature an opponent controls enters the battlefield, you may pay {g}. If you do, that creature loses indestructible and cannot have or gain indestructible for the rest of the game.