Kambal, Consul of Allocation

Whenever an opponent casts a noncreature spell, that player loses 2 life and you gain 2 life.

Swamp

Scholar of Athreos

{2}{B}: Each opponent loses 1 life. You gain life equal to the life lost this way.

Hidden Stockpile

Revolt — At the beginning of your end step, if a permanent left the battlefield under your control this turn, create a 1/1 colorless Servo artifact creature token.
{1}, Sacrifice a creature: Scry 1.

Fumigate

Destroy all creatures. You gain 1 life for each creature destroyed this way.

Authority of the Consuls

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

Mausoleum Secrets

Undergrowth — Search your library for a black card with mana value less than or equal to the number of creature cards in your graveyard, reveal it, put it into your hand, then shuffle.

Plains

Gonti's Machinations

Whenever you lose life for the first time each turn, you get {E}. (You get an energy counter. Damage causes loss of life.)
Pay {E}{E}, Sacrifice this enchantment: Each opponent loses 3 life. You gain life equal to the life lost this way.

Kunoros, Hound of Athreos

Vigilance, menace, lifelink
Creature cards in graveyards can't enter the battlefield.
Players can't cast spells from graveyards.