Kalastria Healer

Rally — Whenever Kalastria Healer or another Ally you control enters, each opponent loses 1 life and you gain 1 life.

Ob Nixilis Reignited

+1: You draw a card and you lose 1 life.
−3: Destroy target creature.
−8: Target opponent gets an emblem with "Whenever a player draws a card, you lose 2 life."

Eldrazi Devastator

Reckless Cohort

Reckless Cohort attacks each combat if able unless you control another Ally.

Chasm Guide

Rally — Whenever Chasm Guide or another Ally you control enters, creatures you control gain haste until end of turn.

Void Winnower

Your opponents can't cast spells with even mana values. (Zero is even.)
Your opponents can't block with creatures with even mana values.

Mortuary Mire

Mortuary Mire enters tapped.
When Mortuary Mire enters, you may put target creature card from your graveyard on top of your library.
{T}: Add {B}.

Nirkana Assassin

Whenever you gain life, Nirkana Assassin gains deathtouch until end of turn. (Any amount of damage it deals to a creature is enough to destroy it.)

Snow-Covered Swamp

Defiant Bloodlord

Flying
Whenever you gain life, target opponent loses that much life.

Smoldering Marsh

({T}: Add {B} or {R}.)
Smoldering Marsh enters tapped unless you control two or more basic lands.

Ally Encampment

{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast an Ally spell.
{1}, {T}, Sacrifice Ally Encampment: Return target Ally you control to its owner's hand.

Hedron Blade

Equipped creature gets +1/+1.
Whenever equipped creature becomes blocked by one or more colorless creatures, it gains deathtouch until end of turn. (Any amount of damage it deals to a creature is enough to destroy it.)
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Bloodbond Vampire

Whenever you gain life, put a +1/+1 counter on Bloodbond Vampire.

Volcanic Upheaval

Retreat to Valakut

Landfall — Whenever a land you control enters, choose one —
• Target creature gets +2/+0 until end of turn.
• Target creature can't block this turn.

Geyserfield Stalker

Menace (This creature can't be blocked except by two or more creatures.)
Landfall — Whenever a land you control enters, Geyserfield Stalker gets +2/+2 until end of turn.

Lavastep Raider

{2}{R}: Lavastep Raider gets +2/+0 until end of turn.

Shatterskull Recruit

Menace (This creature can't be blocked except by two or more creatures.)

Swarm Surge

Devoid (This card has no color.)
Creatures you control get +2/+0 until end of turn. Colorless creatures you control also gain first strike until end of turn.