msem-instigator

Bwema, the Ruthless enters with your choice of two different counters on it from among menace, first strike, vigilance, and lifelink.

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.

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.

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.

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

Target creature gets +1/+1 and gains indestructible until end of turn.

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.

Deathtouch
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.)

Destroy target artifact. Create two 1/1 colorless Servo artifact creature tokens.

Whenever one or more cards leave your graveyard, each opponent loses 1 life and you gain that much life.

When Covert Reinforcement enters, exile target nonland permanent an opponent controls until Covert Reinforcement leaves the battlefield.

This spell costs {2} less to cast if you control a creature with a Tale.
Draw two cards.

You may play lands from your graveyard.