msem-instigator

Create a 3/3 red Giant creature token with haste.
Creatures you control gain double strike until end of turn.

Lazhu, Whisperflame Seer enters with your choice of a trample or +1/+1 counter on him.
Whenever a creature in Lazhu's pack deals damage to a player or planeswalker, draw a card. (Two or more creatures you control with equal power are in a pack.)

Young Dragonheart gets +1/+0 and has first strike as long as you control a legendary creature.

Gain control of target nonland permanent you don't control unless its controller has Bow or Burn deal X damage to them, where X is twice that permanent's mana value. If Bow or Burn was cast from a graveyard, repeat this process for each other nonland permanent they control.
Flashback {6}{R}{R}

Whenever one or more cards are put into an opponent's graveyard from their hand or library, Cackling Tormentor deals 2 damage to any target.

{2}{U}{B}, Sacrifice a creature: Return target creature card from your graveyard to the battlefield with a finality counter on it. It gains myriad. (Whenever it attacks, for each opponent other than defending player, you may put a token that's a copy of this creature onto the battlefield tapped and attacking that player or a planeswalker they control. Exile the tokens at end of combat.)

When Undermarket Favors enters, target player discards a card, then mills four cards.
{1}, Sacrifice Undermarket Favors: Draw a card.

When Dreamsight Well enters, shuffle any number of cards you own from outside the game into your library.
Whenever you cast a creature spell, if you have more cards in your library than each opponent, draw a card.

If another creature with a +1/+1 counter on it you control would die, instead remove a counter from it. If you do, it phases out. (Treat it and anything attached to it as though they don't exist until its controller's next turn.)

Choose one —
• Target creature gets +1/+1 and gains lifelink until end of turn.
• Target creature gets -2/-2 until end of turn.
• Scry 1, then draw a card.

Hazy Coppice enters tapped.
{T}: Add {U} or {B}.
{2}{U}{B}: Until end of turn, Hazy Coppice becomes a 4/4 blue and black Bird creature with with flying and “Whenever this creature attacks or blocks, torment yourself.” It's still a land. (To torment yourself, lose 3 life unless you discard a card or sacrifice a nonland permanent.)

Deathtouch
At the beginning of each opponent's upkeep, that player loses 1 life.

When Paul's Finest Act enters, search your library for a legendary red card, reveal it, put it into your hand, then shuffle.
Creatures you control get +1/+0 as long as you've cast a noncreature spell this turn.

Bloodprice {2}{U} (You may cast this card by sacrificing a creature and paying its bloodprice.)
Draw two cards. If you cast this spell for its bloodprice, instead scry 4, then draw two cards.

Whenever Doomsower or another Human you control dies, you draw a card and you lose life equal to that creature's power.

Exile target creature you control and each creature blocking or blocked by it.

Whenever Harvester of Secrets or another creature enters from your graveyard, you may draw a card.
Unearth {2}{U}{B} ({2}{U}{B}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the end step or if it would leave the battlefield. Unearth only as a sorcery.)

Hidden Prowess deals 2 damage to target creature. When that creature dies this turn, create a 1/1 red Elemental creature token.

Whenever a creature or planeswalker enters under an opponent's control, sacrifice Rune-Scribe's Trap unless you pay {R}. If you sacrifice it, it deals 6 damage to that permanent.

Enchant opponent
Cards in enchanted player's graveyard lose all abilities and all names.
If enchanted player would mill one or more cards, they instead mill that many cards plus X, where X is the number of Curses attached to them.

{2}: Avaricious Ghul gets +1/+1 until end of turn. If mana from a Treasure was spent to activate this ability, put a +1/+1 counter on Avaricious Ghul instead.

At the beginning of each end step, if a creature an opponent controlled died this turn, return a creature card from your graveyard to the battlefield.

Whenever one or more creature cards leave your graveyard, Hadik's Cohort deals 2 damage to target opponent.

Okrophore's power and toughness are each equal to the number of colorless cards in your graveyard.

Enchant creature
Enchanted creature gets -3/-3.