msem-instigator

Flash
Oscanthor, Trader's Ruin can't be blocked.
Whenever a creature you control deals combat damage to a player, draw a card.

Exile two target cards from your graveyard. If they share a card type, draw a card. (Then exile this card. You may cast the creature later from exile.)

Whenever Birthing Elemental or another nontoken creature you control dies, create a 1/1 green Saproling creature token.

Menace
Whenever you cast a spell from anywhere other than your hand, each opponent discards a card if it's your turn. Otherwise, each opponent loses 2 life.

Whenever a nontoken creature you control dies, create a 1/1 black Worm creature token.
Sacrifice Fertile Grave: Create a 1/1 black Worm creature token.

As an additional cost to cast this spell, sacrifice an artifact or creature.
Draw two cards.

{3}{G}: Elder Rootwallas gets +4/+2 until end of turn. Activate only once each turn.

[+1]: Search each player's graveyard, hand, and library for any number of cards with the same name as target nonbasic card in a graveyard and exile them. Then each player shuffles.
[–2]: Each player draws two cards, then each opponent exiles two cards at random from their hand.
[–5]: You may cast a card exiled with Mei Liva without paying its mana cost.

Concord — When Coral Bruiser enters, if there are four or more card types among permanents you control, put target creature you don't control into its owner's library third from the top.

I, II — Look at the top four cards of your library. You may reveal a permanent card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.
Discovery — At the beginning of your end step, you may put a permanent card from your hand onto the battlefield.

Destroy target creature.

Archive 2 (As this enters, shuffle the top two cards of your main library into a new face up library. Sacrifice this after the archived library is empty.)
Whenever you draw a card from the archived library, target creature you control gains vigilance and indestructible until end of turn.

Mark (Whenever this creature attacks, mark target creature until end of turn.)
Alley Hunter has lifelink as long as it's blocked by a marked creature.

First strike
{4}{W}, {T}: Target creature gets +2/+1 and gains first strike until end of turn. Activate only as a sorcery.

Destroy all creatures and planeswalkers with mana value X or less.

Equipped creature gets +1/+1 and has menace.
Equip {R}

Advance {2}{W} (Cast this for {2}{W} to advance it as it enters. {2}{W}: Advance this as a sorcery.)
Whenever Hoverstepper advances, target creature gets +1/+1 and gains flying until end of turn.

Target creature gets -2/-2 until end of turn. Mill two cards.

Destroy target creature with no counters on it and no permanents attached to it.

Enchant creature
Enchanted creature gets +1/+1 and has “At the beginning of each end step, you gain 1 life.”

(Choose only one work as a sorcery to add its ability.)
When Juyu Offering Pool enters, reveal the top five cards of your library. You may put a noncreature card from among them into your hand. Put the rest on the bottom of your library in any order.
{1}{U}: Scales of Shara
Whenever you cast a noncreature spell, put a +1/+1 counter on target creature you control.
{6}{U}{U}: Eye of Shojiro
Whenever you cast a noncreature spell, create an 8/8 blue Kraken creature token.

When Infectious Corpse dies, each player loses 2 life.

Bleed {2}{B} (You may cast this spell for its bleed cost if an opponent has lost life this turn.)
Destroy target creature. Its controller loses 2 life.

When Memory Figment is put into your graveyard from your hand or library, you may exile it. If you do, for as long as it remains exiled, you may cast it. It costs {2} less to cast this way.

Counter target spell. Spells its controller casts cost {2} more to cast this turn.