Akoum Hellhound

Landfall — Whenever a land you control enters, Akoum Hellhound gets +2/+2 until end of turn.

Ageless Entity

Whenever you gain life, put that many +1/+1 counters on Ageless Entity.

Ancient Greenwarden

Reach (This creature can block creatures with flying.)
You may play lands from your graveyard.
If a land entering the battlefield causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Animar, Soul of Elements

Protection from white and from black
Whenever you cast a creature spell, put a +1/+1 counter on Animar, Soul of Elements.
Creature spells you cast cost {1} less to cast for each +1/+1 counter on Animar.