Mortality Spear

This spell costs {2} less to cast if you gained life this turn.
Destroy target nonland permanent.

Deathgreeter

Whenever another creature dies, you may gain 1 life.

Dina, Soul Steeper

Whenever you gain life, each opponent loses 1 life.
{1}, Sacrifice another creature: Dina, Soul Steeper gets +X/+0 until end of turn, where X is the sacrificed creature's power.

Essence Warden

Whenever another creature enters, you gain 1 life.

Marauding Blight-Priest

Whenever you gain life, each opponent loses 1 life.

Prosperous Innkeeper

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