msem-instigator

Return target instant or sorcery card with mana value 3 or less and without reconstruct from your graveyard to your hand.
Reconstruct {6}{U} (You may cast this from your graveyard for its reconstruct cost reduced by the mana value of a permanent you sacrifice as you cast it this way. Then exile this.)

Counter target spell. Tap all lands that spell's controller controls and that player loses all unspent mana.

When Stillmarsh Brinecatcher enters, return another target nonland permanent to its owner's hand.
At the beginning of your end step, if you control a permanent with mana value 5 or greater, you may sacrifice Stillmarsh Brinecatcher. If you do, draw a card and create a 3/2 colorless Horror creature token.

Reveal the top four cards of your library. You may put one into your hand and the rest into your graveyard.
Compose (Then if you cast this from your hand, exile it and create a Saga token with “r3—You may cast a copy of this card from exile without paying its mana cost.”)

Gain control of target artifact, creature, or planeswalker if its mana value is 4 or less or if you cast A Sucker for You from a graveyard.
Reconstruct {9}{U}{U}{U} (You may cast this from your graveyard for its reconstruct cost reduced by the mana value of a permanent you sacrifice as you cast it this way. Then exile this.)

Discard a card: Unseen Maniac gets +1/+1 and can't be blocked this turn.
Whenever Unseen Maniac deals combat damage to a player, draw a card.

Until end of turn, you may cast creature spells as though they had flash.
Creatures you control can't be the targets of spells or abilities your opponents control this turn.

Counter up to one target spell unless its controller pays {2}. Until end of turn, you may cast spells as though they had flash.

{T}: Scry 1.
{1}{U}, {T}: Draw a card.

This spell costs {1} less to cast for each instant and sorcery card in your graveyard.
[+1]: Create a 2/2 blue Elemental Illusion creature token with flying and “Whenever this becomes the target of a spell, sacrifice it.”
[–3]: Return up to one other target nonland permanent to its owner's hand. Draw a card.

Sabotage — Whenever an opponent or permanent an opponent controls becomes the target of a spell you control, return target creature card with mana value 3 or less from your graveyard to the battlefield.

Creatures you don't control get -1/-1.
Mirage {1}{B} (You may cast this spell as though it had flash for its mirage cost. If you do, sacrifice it at the beginning of the next cleanup step.)

Once during each of your turns, when a card is put into a graveyard from anywhere, you may cast it. You may spend mana of any color to cast that spell.
When Arroyo, Infinitely Branching is put into your graveyard from anywhere, you may cast it.

Flying
Persist (When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)
When Bitter Corvus enters, you may reveal the top X cards of your library, where X is Bitter Corvus' power. You may put up to one card revealed this way into your hand. You lose life equal to its mana value. Put the rest into your graveyard.

Whenever Blood Artist or another creature dies, target player loses 1 life and you gain 1 life.

Target opponent sacrifices a creature.
Rerun (If you cast this from your hand, exile it as it resolves. Whenever a creature you control dies, you may cast this card from exile without paying its mana cost.)

When Carrion Scythe enters, if you cast it, you may return target creature card from your graveyard to the battlefield, then attach Carrion Scythe to it.
Equipped creature gets +1/+1 and has deathtouch.
Equip {2}

When Channeler of the Veil enters, create a 1/1 colorless Construct artifact creature token.
Sacrifice another creature: Each opponent loses 1 life.

When Chigau, the Red Market enters, draw a card, then choose a creature card name.
Once each turn, you may cast a creature spell with the chosen name from your graveyard.

Deathtouch
When Corpsecaster Mage enters, if you cast it, target creature card in your graveyard gains arise until end of turn. Its arise cost is equal to its mana cost. (Exile that card from your graveyard and pay its arise cost: Create a token that's a copy of it except it's a black Zombie in addition to its other types, has no mana cost, and can't block. Arise only as a sorcery.)

Glitch {1} (Remove one [restriction] for each time you pay the glitch cost.)
Target opponent reveals their hand. You choose a [noncreature,] nonland card [with mana value 3 or less] from among them. That player discards that card.

Menace, haste, decayed (This can't block. When it attacks, sacrifice it at end of combat.)
At the beginning of combat on each of your turns, if you have three or more creature cards in your graveyard and haven't controlled a creature named Crypt Gnawer this turn, return Crypt Gnawer from your graveyard to the battlefield.

Search your library for a card, exile it face down, then shuffle. For as long as that card remains exiled, you may cast it. It costs {2} more to cast this way if you don't control a legendary creature as you cast that spell.

You don't lose the game for having 0 or less life.
Whenever you're dealt damage, mill that many cards.
{B}, Pay 2 life: Put target card in your graveyard on the bottom of your library.

This spell costs {2} less to cast for each creature that died this turn.
Flying, trample