Lurking Crocodile 

Creature — Crocodile
Bloodthirst 1 (If an opponent was dealt damage this turn, this creature enters with a +1/+1 counter on it.) Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
Legality
standardNOT LEGALpioneerNOT LEGALmodernLEGALlegacyLEGALvintageLEGALcommanderLEGAL