msem-instigator

{3}{R}: Attacking creatures you control get +1/+0 until end of turn.

Golden age (If you cast an instant or sorcery spell, activated a nonmana ability, and attacked this turn, enter a renaissance for this game.)
{1}{R}: Mieng gains flying until end of turn.
Whenever Mieng attacks, create a 4/4 red Dragon creature token with flying that's tapped and attacking. Exile that token at end of combat unless you're in a renaissance.

Mine Delver has first strike as long as it's embattled. (A creature is embattled if it has a counter on it or a permanent you control attached to it.)

{1}{R}, {T}: Target creature gains shimmer until end of turn. (Whenever it attacks this turn, create a tapped and attacking token that's a copy of it. Exile that token at the beginning of the end step.)

Sabotage — Whenever an opponent or permanent an opponent controls becomes the target of a spell you control, put a +1/+1 counter on Mirrorcast Battlemage.
Remove three +1/+1 counters from Mirrorcast Battlemage: Copy target instant or sorcery spell you control. You may choose new targets for the copy. Activate only once each turn.

Other creatures you control get +2/+0 and have menace.
Whenever another creature you control dies, if it wasn't sacrificed, sacrifice a creature.

Gestalt (When this or another creature enters under your control, you may merge it with the one in play, keeping counters and attachments. They become the permanent on top plus all abilities from under it.)
Double strike
If this creature would deal noncombat damage, it deals double that damage instead.

Motley Crew has no name while it's being cast. (It will always make first contact.)
{2}{R}: Creatures you control named Motley Crew get +1/+0 until end of turn.

Whenever a land you control enters, put a +1/+1 counter on Mountain Runt, then it deals 1 damage to up to one target creature you don't control.
When Mountain Runt has three or more +1/+1 counters on it, remove them all and transform it.

When Mouthpiece of Yhzag enters, you may have target opponent create a tapped 1/1 colorless Human creature token.
Whenever Mouthpiece of Yhzag attacks, gain control of target Human creature you don't control with mana value 3 or less until end of turn. Tap it. It's attacking.

As an additional cost to cast this spell, pay {3} or discard a card.
Respawn (When this creature dies, if it attacked this turn, return it to its owner's hand.)

Whenever you cast a noncreature spell, Novice Pyromancer deals 1 damage to target player or planeswalker.

{T}, Discard a card: Draw a card.
{2}{R}, {T}: Copy target instant or sorcery spell you control. You may choose new targets for the copy. Activate only if you have four or more instant and/or sorcery cards in your graveyard.

Whenever Passionate Painter becomes untapped, you may discard a card. If you do, draw a card, then transform Passionate Painter.

{1}{R}: Performer of Desire gets +1/+1 and gains menace until end of turn. Then if its power is 4 or greater, you may transform it.

Whenever a noncreature permanent enters, Petaldiver deals 1 damage to that permanent's controller.

Flying, haste
Whenever Phoenix of Agonas attacks, you may discard a card. If you do, draw a card.
{4}{R}: Return Phoenix of Agonas from your graveyard to your hand. This ability costs {X} less to activate, where X is your devotion to red. (Each {R} in the mana costs of permanents you control counts toward your devotion to red.)

Whenever Practical Battlemage attacks, catalyze. (The next spell you cast this turn costs {1} less to cast.)

As an additional cost to cast this spell, pay {2} or reveal an instant or sorcery card from your hand.

When Primordial Progenitor dies, create two 1/1 red Elemental creature tokens.

Flying
{3}: Prismscale Dragon gets +1/+1 until end of turn for each color of mana spent to activate this ability.

Menace, haste

Chronicle (As this enters and after your draw step, add a lore counter. Stop after III.)
[Lore I-II] Purphoros's Gemback deals 1 damage to target player or planeswalker.
[Lore III] Create a Treasure token. (It's an artifact with “{T}, Sacrifice this artifact: Add one mana of any color.”)

{T}: Quill Sniper deals 1 damage to any target if it's an opponent or if you control a storied permanent. (Enchantments and legendary permanents are storied.)

When Rakkiri Aspirant enters, if you control an embattled creature, exile the top card of your library. Until end of turn, you may play that card. (A creature is embattled if it has a counter on it or has a permanent you control attached to it.)