Mephitic Vapors

All creatures get -1/-1 until end of turn.
Surveil 2. (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)

Revenge of Ravens

Whenever a creature attacks you or a planeswalker you control, that creature's controller loses 1 life and you gain 1 life.

Unlikely Aid

Target creature gets +2/+0 and gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Orzhov Guildgate

This land enters tapped.
{T}: Add {W} or {B}.

Sorin's Thirst

Sorin's Thirst deals 2 damage to target creature and you gain 2 life.

Resolute Rider

{W/B}{W/B}: This creature gains lifelink until end of turn.
{W/B}{W/B}{W/B}: This creature gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Agonizing Syphon

Agonizing Syphon deals 3 damage to any target and you gain 3 life.

Plains

Consume

Target player sacrifices a creature with the greatest power among creatures they control. You gain life equal to its power.

Consecrate

Exile target card from a graveyard.
Draw a card.

Consecrate // Consume

Deathless Knight

Haste
When you gain life for the first time each turn, return this card from your graveyard to your hand.

Ill-Gotten Inheritance

At the beginning of your upkeep, this enchantment deals 1 damage to each opponent and you gain 1 life.
{5}{B}, Sacrifice this enchantment: It deals 4 damage to target opponent and you gain 4 life.

Swamp

Disenchant

Bloodthirsty Aerialist

Flying
Whenever you gain life, put a +1/+1 counter on this creature.

Daybreak Chaplain

Lifelink (Damage dealt by this creature also causes you to gain that much life.)

Vicious Rumors

Vicious Rumors deals 1 damage to each opponent. Each opponent discards a card, then mills a card. You gain 1 life.

Trapped in the Tower

Enchant creature without flying
Enchanted creature can't attack or block, and its activated abilities can't be activated.

Orzhov Locket

{T}: Add {W} or {B}.
{W/B}{W/B}{W/B}{W/B}, {T}, Sacrifice this artifact: Draw two cards.

Twinblade Paladin

Whenever you gain life, put a +1/+1 counter on this creature.
As long as you have 25 or more life, this creature has double strike. (It deals both first-strike and regular combat damage.)

Outflank

Outflank deals damage to target attacking or blocking creature equal to the number of creatures you control.

Cryptic Caves

{T}: Add {C}.
{1}, {T}, Sacrifice this land: Draw a card. Activate only if you control five or more lands.

Corpse Knight

Whenever another creature you control enters, each opponent loses 1 life.

Ajani's Pridemate

Whenever you gain life, put a +1/+1 counter on this creature.

Grasping Thrull

Flying
When this creature enters, it deals 2 damage to each opponent and you gain 2 life.