msem-instigator

This spell costs {1} less to cast for each card you've discarded this turn.
Draw three cards.

Sacrifice a creature: Surveil 1. (Look at the top card of your library. You may put that card into your graveyard.)

This spell costs {1} less to cast for each creature you attacked with this turn. (Those creatures don't have to still be on the battlefield.)
Flying

{W}, {T}: Tap target creature.

Return target nonland permanent to its owner's hand.
Agonize (You may cast this card from your graveyard by putting a -1/-1 counter on a creature you control in addition to paying its other costs. Then exile this card.)

Target creature you control gets +1/+1 until end of turn. It deals damage equal to its power to target creature you don't control.

Search your library for up to two basic land cards, reveal those cards, and put one onto the battlefield tapped and the other into your hand, then shuffle.
Coalesce {7}{G} (You may cast this from your graveyard for {7}{G}. If you do, it enters as a Horror creature after it resolves. Exile it if it would leave the battlefield or not resolve.)

Cleave deals 1 damage to each opponent and 1 damage to each creature and planeswalker your opponents control.

Return target creature you control and target creature you don't control to their owners' hands.

Whenever you cast an instant or sorcery spell, Clever Infiltrator gets +2/+0 until end of turn and can't be blocked this turn.

Equipped creature has flying.
Equip {3}

When Climber's Outfit enters, search your library for a basic land card, reveal it, put it into your hand, then shuffle.
Equipped creature has reach.
Equip {1}

Create a 2/2 black Zombie creature token.
Tether (Then if you cast this from your hand, you may exile it tethered to a creature you control. When it dies, you may cast this from exile without paying its mana cost.)

Target creature gets -4/-4 until end of turn.

Whenever you cast a noncreature spell, you may shuffle target card an opponent owns in exile into its owner's library.

{T}, Tap an untapped creature you control: Choose one —
• Add one mana of any color.
• Target player loses 2 life.
• Target player gains 3 life.
• Target player mills four cards.

Clocktower Hideout enters tapped.
When Clocktower Hideout enters, look at the top card of your library. You may put it into your graveyard.
{T}: Add {B} or {R}.

Create a 0/0 blue Construct artifact creature token. Put X +1/+1 counters on it, where X is one plus the total number of noncreature, nonland cards in your graveyard.

Puzzlebox (Begin the game with this and another card you own from outside the game in the command zone, locked. That card is face down until you unlock this.)
Tap four untapped creatures you control: Unlock Clockwork Astrolarium. If the revealed card is white, put it into your hand. Otherwise, put it on top of your library.

When Cloister enters, exile another target nonland permanent you control and target nonland permanent you don't control until Cloister leaves the battlefield.
{2}{W}, Sacrifice Cloister: You gain 5 life.

Target creature gets +2/+0 until end of turn and can't be blocked this turn.

Trample
You may spend black and green mana as though it were mana of any color.
Whenever Closing-Act Abomination attacks, look at the top X cards of your library, where X is the number of colors among cards in your graveyard. Put up to one of them into your hand and the rest on the bottom of your library in a random order.

Flying
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
At the beginning of your end step, you may untap another target permanent.

Stampede — Whenever Cloud's Roar Avenger and a creature with greater power attack, tap up to one target creature.

({T}: Add {U}.)
Cloudbank enters tapped.
When Cloudbank enters, target creature gains flying until end of turn.