msem-instigator

Menace, haste
Cadence (Whenever you cast a spell, if its mana value is greater than this creature's power, put a +1/+1 counter on this creature.)

I — Exile the top card of your library face down.
II — Exile any number of cards from your hand face down.
III — Calamity of Yore deals damage to target creature or planeswalker equal to the number of cards you own in exile. Return all cards exiled with Calamity of Yore to their owners' hands.

Call of the Abyss deals 3 damage to any target and you gain 3 life.

Canid Simulacrum enters with each counter on it from among +1/+1, flying, first strike, deathtouch, lifelink, menace, reach, shield, trample, and vigilance. (If it would be dealt damage or destroyed, remove a shield counter from it instead.)
Whenever a creature you control enters, move two random counters from Canid Simulacrum onto that creature.

You may cast this spell with no targets for {2}{R}. If you do, as it resolves, create a 1/1 red Hound creature token, then attach Canine Acumen to that token.
Enchant creature
Enchanted creature gets +2/+0 and has first strike.

Haste
Caulte Axeslinger gets +2/+2 as long as any opponent lost exactly 3 life this turn.

Other nonland permanents enter tapped.
Your opponents can't activate abilities of tapped permanents.

When Cave Eel enters, look at the top three cards of your library. Put one on top and the rest on the bottom in any order.

Double strike
Motley — As long as there are five or more names among nonland permanents you control, Champion of Blades has vigilance, trample, and haste.

Trample
Whenever a lore counter is put on a Saga you control, Chimperial Guard gets +2/+2 until end of turn.

{1}, Sacrifice a creature: Put a +1/+1 counter on Chitterrax, then each opponent loses 1 life and you gain 1 life.

Flying
Lands you control have “{T}: Add one mana of any color.”
As long as you control seven or more lands, creatures you control have trample, haste, and hexproof.

Equipped creature has haste.
Sacrifice Cinderblade: Equipped creature gains +2/+2 until end of turn.
Equip {1}

Whenever you cast an instant or sorcery spell, you may exile that card instead of putting it anywhere else as it resolves.
At the beginning of your upkeep, Clash Reactor deals X damage to each opponent, where X is the number of colors of cards exiled with Clash Reactor.

({T}: Add {W}, {U}, or {B}.)
Coastal Dominion enters tapped.

At the beginning of combat on your turn, target creature you control has base power and toughness 4/4 until end of turn.

Haste
Coldhearted Explorer can't block.

Haste
When Collapsing Star Viper enters, you may tap target permanent with mana value X or less.
At the beginning of your upkeep, return Collapsing Star Viper to its owner's hand.

{T}: Add one mana of any color.
Augmented — Whenever a nontoken creature you control enters, if you've spent {W}{U}{B}{R}{G} to cast spells this turn, put a +1/+1 counter on it.

When Colony Queen enters, create three 1/1 green Insect creature tokens.
Insect tokens you control have flying and deathtouch.

When Colony Soldier enters, create a 1/1 green Insect creature token.

Whenever Combat Technician attacks, create a 1/1 colorless Servo artifact creature token that's tapped and attacking. Then Combat Technician gets +1/+1 until end of turn for each artifact you control.

Put a +1/+1 counter on target creature you control. It can't be blocked by more than one creature this turn.
Whenever a creature you control attacks alone, return Come Out and Play from your graveyard to your hand.

This spell costs {X} less to cast, where X is the greatest power among creatures you control.
Tap up to three target creatures. They don't untap during their controller's next untap step.

Discard a card: Concealed Slasher gets +1/+1 until end of turn and can't be blocked this turn.