Ajani, Caller of the Pride

+1: Put a +1/+1 counter on up to one target creature.
−3: Target creature gains flying and double strike until end of turn.
−8: Create X 2/2 white Cat creature tokens, where X is your life total.

Golden-Scale Aeronaut

Backup 1 (When this creature enters, put a +1/+1 counter on target creature. If that's another creature, it gains the following ability until end of turn.)
Flying

Boon-Bringer Valkyrie

Backup 1 (When this creature enters, put a +1/+1 counter on target creature. If that's another creature, it gains the following abilities until end of turn.)
Flying, first strike, lifelink

Mirror-Style Master

Backup 1 (When this creature enters, put a +1/+1 counter on target creature. If that's another creature, it gains the following ability until end of turn.)
Whenever this creature attacks, for each attacking modified creature you control, create a tapped and attacking token that's a copy of that creature. Exile those tokens at end of combat. (Equipment, Auras you control, and counters are modifications.)

Ajani, Wise Counselor

+2: You gain 1 life for each creature you control.
−3: Creatures you control get +2/+2 until end of turn.
−9: Put X +1/+1 counters on target creature, where X is your life total.

Guardian Scalelord

Backup 1 (When this creature enters, put a +1/+1 counter on target creature. If that's another creature, it gains the following abilities until end of turn.)
Flying
Whenever this creature attacks, return target nonland permanent card with mana value X or less from your graveyard to the battlefield, where X is this creature's power.

Fearless Skald

Backup 1 (When this creature enters, put a +1/+1 counter on target creature. If that's another creature, it gains the following ability until end of turn.)
Double strike

Redcap Heelslasher

Backup 1 (When this creature enters, put a +1/+1 counter on target creature. If that's another creature, it gains the following ability until end of turn.)
First strike

Voldaren Thrillseeker

Backup 2 (When this creature enters, put two +1/+1 counters on target creature. If that's another creature, it gains the following ability until end of turn.)
{1}, Sacrifice this creature: It deals damage equal to its power to any target.

Bola Slinger

Backup 1 (When this creature enters, put a +1/+1 counter on target creature. If that's another creature, it gains the following ability until end of turn.)
Whenever this creature attacks, tap target artifact or creature an opponent controls.

Cragsmasher Yeti

Mountaincycling {2} ({2}, Discard this card: Search your library for a Mountain card, reveal it, put it into your hand, then shuffle.)
Backup 2 (When this creature enters, put two +1/+1 counters on target creature. If that's another creature, it gains the following ability until end of turn.)
Trample

Enduring Bondwarden

Backup 1 (When this creature enters, put a +1/+1 counter on target creature. If that's another creature, it gains the following ability until end of turn.)
When this creature dies, put its counters on target creature you control.

Advance Scout

First strike
{W}: Target creature gains first strike until end of turn.

Mirror-Shield Hoplite

Vigilance
Whenever a creature you control becomes the target of a backup ability, copy that ability. You may choose new targets for the copy. This ability triggers only once each turn.

Agrus Kos, Eternal Soldier

Vigilance
Whenever Agrus Kos, Eternal Soldier becomes the target of an ability that targets only it, you may pay {1}{R/W}. If you do, copy that ability for each other creature you control that ability could target. Each copy targets a different one of those creatures. ({R/W} can be paid with either {R} or {W}.)

Akki Drillmaster

{T}: Target creature gains haste until end of turn.

Alabaster Mage

{1}{W}: Target creature you control gains lifelink until end of turn. (Damage dealt by the creature also causes its controller to gain that much life.)

Death-Greeter's Champion

Dash {3}{R} (You may cast this spell for its dash cost. If you do, it gains haste, and it's returned from the battlefield to its owner's hand at the beginning of the next end step.)
Backup 1 (When this creature enters, put a +1/+1 counter on target creature. If that's another creature, it gains the following ability until end of turn.)
Double strike

Ajani Steadfast

+1: Until end of turn, up to one target creature gets +1/+1 and gains first strike, vigilance, and lifelink.
−2: Put a +1/+1 counter on each creature you control and a loyalty counter on each other planeswalker you control.
−7: You get an emblem with "If a source would deal damage to you or a planeswalker you control, prevent all but 1 of that damage."

Backup Agent

When Backup Agent enters, put a +1/+1 counter on target creature.

Sigiled Sentinel

Backup 1 (When this creature enters, put a +1/+1 counter on target creature. If that's another creature, it gains the following ability until end of turn.)
Vigilance

Adarkar Valkyrie

Flying, vigilance
{T}: When target creature other than Adarkar Valkyrie dies this turn, return that card to the battlefield under your control.

Hangar Scrounger

Backup 1 (When this creature enters, put a +1/+1 counter on target creature. If that's another creature, it gains the following ability until end of turn.)
Whenever this creature becomes tapped, you may discard a card. If you do, draw a card.