Craterhoof Behemoth

Haste
When this creature enters, creatures you control gain trample and get +X/+X until end of turn, where X is the number of creatures you control.

Rocco, Cabaretti Caterer

When Rocco enters, if you cast it, you may search your library for a creature card with mana value X or less, put it onto the battlefield, then shuffle.

Phlage, Titan of Fire's Fury

When Phlage enters, sacrifice it unless it escaped.
Whenever Phlage enters or attacks, it deals 3 damage to any target and you gain 3 life.
Escape—{R}{R}{W}{W}, Exile five other cards from your graveyard. (You may cast this card from your graveyard for its escape cost.)

Warleader's Call

Creatures you control get +1/+1.
Whenever a creature you control enters, this enchantment deals 1 damage to each opponent.

Prosperous Innkeeper

When this creature enters, create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")
Whenever another creature you control enters, you gain 1 life.

Soul's Attendant

Whenever another creature enters, you may gain 1 life.

Serra Ascendant

Lifelink (Damage dealt by this creature also causes you to gain that much life.)
As long as you have 30 or more life, this creature gets +5/+5 and has flying.

Essence Warden

Whenever another creature enters, you gain 1 life.

Wirewood Symbiote

Return an Elf you control to its owner's hand: Untap target creature. Activate only once each turn.

Soul Warden

Norin the Wary

When a player casts a spell or a creature attacks, exile Norin. Return it to the battlefield under its owner's control at the beginning of the next end step.

Guide of Souls

Whenever another creature you control enters, you gain 1 life and get {E} (an energy counter).
Whenever you attack, you may pay {E}{E}{E}. When you do, put two +1/+1 counters and a flying counter on target attacking creature. It becomes an Angel in addition to its other types.

Moonshaker Cavalry

Flying
When this creature enters, creatures you control gain flying and get +X/+X until end of turn, where X is the number of creatures you control.