Gray Harbor Merfolk 
Creature — Merfolk Rogue
This creature can't be blocked. This creature gets +2/+0 as long as you control a commander that's a creature or planeswalker.
Legality
standardNOT LEGALpioneerNOT LEGALmodernNOT LEGALlegacyLEGALvintageLEGALcommanderLEGAL