Soul Warden

Whenever another creature enters, you gain 1 life.

Myrkul, Lord of Bones

As long as your life total is less than or equal to half your starting life total, Myrkul, Lord of Bones has indestructible.
Whenever another nontoken creature you control dies, you may exile it. If you do, create a token that's a copy of that card, except it's an enchantment and loses all other card types.

Authority of the Consuls

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

Heartless Summoning

Creature spells you cast cost {2} less to cast.
Creatures you control get -1/-1.

Essence Warden

Myrkul's Edict

Roll a d20.
1—9 | Choose an opponent. That player sacrifices a creature of their choice.
10—19 | Each opponent sacrifices a creature of their choice.
20 | Each opponent sacrifices a creature with the greatest power among creatures that player controls.