Impact Tremors

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

Arabella, Abandoned Doll

Whenever Arabella attacks, it deals X damage to each opponent and you gain X life, where X is the number of creatures you control with power 2 or less.

Hinterland Sanctifier

Whenever another creature you control enters, you gain 1 life.

Dazzling Angel

Flying
Whenever another creature you control enters, you gain 1 life.

Hare Apparent

When this creature enters, create a number of 1/1 white Rabbit creature tokens equal to the number of other creatures you control named Hare Apparent.
A deck can have any number of cards named Hare Apparent.