Splinter of the Sewer

+3: All Mutant Ninja creatures get +1/+1 and gain Indestrucible
-1: Turn this Planeswalker into a X/X Mutant Ninja Creature until the end of the turn. X being the cards Loyalty.
-10: All Mutant Ninja Creatures on the field get +3/+3 and gain Indestructable. All your creatures attack target opponents life directly.