msem-instigator

{T}: Add {C}.
{T}: Add {C}{C}{C}. Spend this mana only to pay advance costs.

Fire from Above deals 2 damage to target opponent and each creature with flying that player controls.

Chosen one ({W}{U}{B}{R}{G}: Transform this permanent.)
At the beginning of combat on your turn, create a 1/1 red Warrior creature token with haste. That token attacks this combat if able.

Trample, haste
Whenever Lisseria, General of Kanaa attacks, you may exchange its power with the power of target creature defending player controls until end of turn.

First strike
Mauling Mother gets +1/+1 for each other creature you control.

Recruit. (Create a 0/0 white Soldier Army creature token, then put a +1/+1 counter on each Army you control.)
Armies you control gain trample until end of turn.

{T}: Add {C}.
Tap an untapped creature you control: Dragonwall Gates becomes a 0/4 Wall artifact creature with defender until end of turn. It's still a land.

Renown 2 (When this creature deals combat damage to a player, if it isn't renowned, put two +1/+1 counters on it and it becomes renowned.)
Whenever a creature you control becomes renowned, draw a card.

{T}, Sacrifice Aether Gateway: Create a tapped Plains token, Island token, Swamp token, Mountain token, or Forest token.

If you would create an Army token while Mehr's Unending Horde is in your graveyard, you may instead return Mehr's Unending Horde from your graveyard to the battlefield.
Counters remain on Mehr's Unending Horde as it moves to any zone other than a player's hand or library.

Deathtouch
Whenever a creature dealt damage by Rabid Rodent this turn dies, put a +1/+1 counter on Rabid Rodent.
{2}, Remove a +1/+1 counter from Rabid Rodent: Regenerate Rabid Rodent.

Flying, haste
Whenever Grieving Revenant attacks, it deals 1 damage to each other creature you control.

Flying
Whenever Keeper of Twisted Light attacks, you gain 3 life.

When Mental Supremacist enters, choose target creature you don't control. That creature has base power and toughness 1/1 and loses all abilities for as long as you control Mental Supremacist.

Flash
When Purehorn Rescuer enters, return target permanent card with mana value X or less from your graveyard to the battlefield, where X is your devotion to white. (Each {W} in the mana costs of permanents you control counts toward your devotion to white.)

Whenever The First Idol attacks, create an Idol token. (It's an artifact with “{1}, Sacrifice this artifact: Put a +1/+1 counter on target creature. Activate only as a sorcery.”)
Sacrifice three Idols: Return The First Idol from your graveyard your hand.

Whenever one or more other creatures you control die, put a +1/+1 counter on Keeper of Tradition.

Enchant artifact
Enchanted artifact is an Equipment and has “Equipped creature gets +2/+0” and equip {0}.

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Whenever you cast an instant or sorcery spell, you may draw a card. If you do, discard a card.

As Alratha, Pearl of the Sand Sea enters, you may have an opponent investigate. If you don't, it enters tapped.
{T}: Add {U}.
{1}{U}, {T}: Investigate.

At the beginning of each end step, put a +1/+1 counter on equipped creature for each creature that died this turn.
Equip {1}

Flying
Whenever you cast a noncreature spell, you may exchange control of it and target creature. Then the spell's controller may choose new targets for it.

Molting Abomination can't be blocked by creatures with power 2 or less.
Whenever Molting Abomination deals combat damage to a player or planeswalker, create a tapped 3/2 colorless Horror creature token. Put a stun counter on that token. (If a permanent with a stun counter would become untapped, remove one from it instead.)

Destroy target creature or planeswalker.
Compose (Then if you cast this from your hand, exile it and create a Saga token with “r3—You may cast a copy of this card from exile without paying its mana cost.”)