msem-instigator

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.)

{2}{R}, Sacrifice Minefield Bomber: It deals 2 damage to any target.
Cycling {2/R} ({2/R}, Discard this card: Draw a card.)

At the beginning of combat on your turn, create a 1/1 red Cleric creature token with haste.
At the beginning of your end step, sacrifice each Cleric token you control unless you've cast an instant or sorcery spell this turn.

Colossal 3—{6}{R} (You may cast this for its colossal cost to have it enter with three +1/+1 counters; or pay {6}{R} as a sorcery: Put three +1/+1 counters on it if it has none.)

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.)

{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.)

When Mirror Paradigm enters, conjure a card named Data-Point into your hand. (It's a sorcery that costs {2} with “Draw a card.”)
Once each turn, when a sorcery card is put into your graveyard from anywhere, you may copy it. If you do, you may cast the copy. (You still pay its costs.)

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.

Glitch {2} (Remove one [restriction] for each time you pay the glitch cost.)
Create a 3/2 red creature token named Error with trample and haste. [Exile it at the beginning of the next end step.]

{1}{R}, Discard a card: Draw a card. Mist-Valley Minotaurs gets +2/+0 until end of turn.

Dragon spells you cast cost {1} less to cast.
{1}{R}: Until end of turn, Miyoga Dragonsoul becomes a 2/2 red Dragon creature with flying and “{R}: Miyoga Dragonsoul gets +1/+0 until end of turn.” Activate only as a sorcery.

Flying, haste
Miyoga Flameweaver can't block.
Whenever Miyoga Flameweaver attacks, exile the top card of your library. You may play that card until end of turn.

First strike, haste
When Moeru Thunderers enters, if it's not a token, create a token that's a copy of it, except it has no mana cost.

Flash
When Mokuteki Ambusher enters, until end of turn, other creatures you control gain “{T}: This creature deals 1 damage to any target.”

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.

Whenever you cast a noncreature spell, put a hatch counter on Molten Incubation. Then if it has five hatch counters on it, sacrifice it and choose one —
• Create a 5/5 red Dragon creature token with flying.
• Molten Incubation deals 20 damage to each creature.

Molten Ritual deals 3 damage to target creature. If that creature would die this turn, exile it instead.

Gain control of target creature with power 2 or less until end of turn. Untap that creature. It gains haste until end of turn.

Target creature gets +4/+3 until end of turn. Put a trample counter on it.

Vanguard — Whenever a creature you control attacks alone, that creature gets +3/+0 until end of turn.

Assault {2}{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.)
When Monstrous Hila assaults, it deals 3 damage to any target.

First strike

Monumental Siege deals 5 damage divided as you choose among any number of targets. Whenever a creature dealt damage this way this turn dies, 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.”)

({T}: Add {R}.)
Moon of the Lingering Day enters tapped.
{1}{R}, {T}: Scry 1.