Arcbound Mamba is a uncommon Artifact Creature — Snake card from Unknown Event (UNK), collector number UG04.
Deathtouch Poison Modular 2 (This creature enters the battlefield with two +1/+1 counters on it. When it dies, you may put its +1/+1 counters on target player or artifact creature. If they're put on a player this way, they become poison counters.)