Hystrodon

Flying

Whenever this creature deals combat damage to a player, you may draw a card. If you do, discard a card.

Morph (You may cast this card face down as a 2/2 creature for . Turn it face up any time for its morph cost.)

Other Snake creatures you control get +2/+2.

Whenever a Snake you control deals combat damage to a player, you may draw a card.

Whenever one or more non-Human creatures you control deal combat damage to a player, draw a card.

Attacking creatures you control have deathtouch.

Whenever a creature you control deals combat damage to a player, draw a card.

Backup 1, backup 1, backup 1 (When this creature enters, put a +1/+1 counter on target creature. If that's another creature, it gains the following abilities until end of turn. Each backup ability triggers separately.)

Trample

Whenever this creature deals combat damage to a player, put that many +1/+1 counters on it.

Whenever this creature deals combat damage to a player, it explores. (Reveal the top card of your library. Put that card into your hand if it's a land. Otherwise, put a +1/+1 counter on this creature, then put the card back or put it into your graveyard.)