Soul's Attendant

Whenever another creature enters, you may gain 1 life.

Authority of the Consuls

Creatures your opponents control enter tapped.
Whenever a creature an opponent controls enters, you gain 1 life.

Soul Warden

Whenever another creature enters, you gain 1 life.

Mirror Entity

Changeling (This card is every creature type.)
{X}: Until end of turn, creatures you control have base power and toughness X/X and gain all creature types.

Adanto Vanguard

As long as this creature is attacking, it gets +2/+0.
Pay 4 life: This creature gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Plains

Forerunner of the Legion

When this creature enters, you may search your library for a Vampire card, reveal it, then shuffle and put that card on top.
Whenever another Vampire you control enters, target creature gets +1/+1 until end of turn.

Font of Agonies

Whenever you pay life, put that many blood counters on this enchantment.
{1}{B}, Remove four blood counters from this enchantment: Destroy target creature.