msem-instigator

When Meteor Harbinger enters, choose one —
• Meteor Harbinger deals 2 damage to each creature.
• Each player sacrifices two lands.
• Meteor Harbinger deals 2 damage to each of two target players or planeswalkers.

Heroic — Whenever you cast a spell that targets Mira and Kalisti of Akros, copy that spell. You may choose new targets for the copy. (The copy isn't cast. A copy of an Aura spell becomes a token.)

Whenever a creature dealt damage by Mooncursed Howler this turn dies, create a 2/2 red Werewolf creature token with first strike.

Flying
When Novaheart Guardian enters, it deals 4 damage to any target.
Whenever a creature or planeswalker dies, put a +1/+1 counter on Novaheart Guardian.

Menace
Whenever Operative GINGER attacks or you cast a blue or white spell, Operative GINGER deals 1 damage to any target.

Cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)
Flying
Dragon spells you cast have cascade.

Prowess
Whenever Prodigal Spark is dealt damage, it deals that much damage to any target.

When Pyroclastic Maw enters, destroy target land. If that land was nonbasic, Pyroclastic Maw gains haste until end of turn.

Flying, haste
Whenever Pyrus, the Undying Flame attacks, add {R}{R}{R}{R}. You don't lose this mana as steps, phases, and turns end.
{1}{R}: Pyrus gets +1/+0 until end of turn.

Flying
{B}: Target attacking creature gets +1/+1 until end of turn.

Whenever Roaring Illusion attacks alone, for each other creature you control, create a token that's a copy of that creature and that's tapped and attacking. Exile those tokens at the beginning of the next end step.

Trample
Tribute 3 (As this creature enters, an opponent of your choice may put three +1/+1 counters on it.)
When Rockpounding Saurian enters, if tribute wasn't paid, you may destroy up to one target artifact, up to one target land and up to one target Fortress.

Flying
Whenever Rubble Scavenger deals combat damage to a player, you may return target artifact card with mana value 4 or less from your graveyard to the battlefield.

Flying
{1}{R}: Sangrite Dragon gets +2/+0 until end of turn.
Sacrifice another creature: Add {R}{R}.

Menace
Whenever Searing Sandwurm is dealt damage, it deals that much damage to target player or planeswalker.

Flying
Whenever Searshot Dragon deals combat damage to a player, it deals that much damage to target creature that player controls.
{1}{R}: Searshot Dragon gets +1/+0 until end of turn.

Trample, haste
When Soul of the Mountain enters, if it isn't a token, for each two Mountains you control, create a token that's a copy of it.

Flying, haste
Whenever you cast an instant or sorcery spell, Sovereign of Old Jidai gets +1/+0 until end of turn.

When Swiftwheel Slayers enters, audition for red. (Create a 1/1 Construct Actor creature token, a Warrior Role giving 3/2 and trample, or a Wizard Role giving 2/2 and prowess. Roles replace older ones.)
Token creatures you control have haste.

Flying, haste
Whenever The Branded Usurper attacks, it deals 2 damage to any target.
If you would lose the game, instead exile The Branded Usurper. Your life total becomes 0. Until an opponent's next turn, you can't lose the game and you can't gain life. Take an extra turn after this one.

Trample
{4}{R}{R}: Tortle Tinkerer explores. This ability costs {1} less to activate for each artifact you control. (Reveal the top card of your library. Put it into your hand if it's a land. Otherwise, put a +1/+1 counter on this creature, then you may put that card in your graveyard.)

This spell costs {1} less to cast for each foretold card you own in exile, each permanent you control with foretell, and each card with foretell in your graveyard.
Flying
When Tyrant of Prophecies enters, it deals 3 damage to any target.

Trample, haste
When Tyrants of Bundan enters, tap all lands target player controls. They don't untap during their controller's next untap step.

Assault {X}{R}{R} (Whenever this attacks, if it has no +1/+1 counters on it, you may pay its assault cost to put a +1/+1 counter on it.)
Other Elementals you control get +1/+0.
When Unbound Annihilus assaults, create X 1/1 red Elemental creature tokens that are tapped and attacking.

Haste
When Urud Stingswoop enters, it gains flying until end of turn.