msem-instigator

Whenever a creature dies, put a +1/+1 counter on Repository of Thoughts.
At the beginning of each combat, you may move a counter from Repository of Thoughts to target creature.

Return target creature card with mana value 3 or less from your graveyard to the battlefield. You gain 3 life.

(Transforms from Ruined Theater.)
{T}: Add one mana of any color.

Look at the top two cards of your library. Put one into your graveyard and the other back on top.

[+2]: Each player sacrifices a creature. Then each player who did creates a 1/1 white and black Spirit enchantment creature token.
[–X]: You may put an enchantment card with mana value X or less from your hand onto the battlefield.
[–6]: Shuffle, then reveal the top seven cards of your library. Put any number of enchantment cards from among them onto the battlefield. Shuffle the rest into your library.

Whenever you cast an instant or sorcery spell, put a loyalty counter on Reytali of Endless Muses.
[0]: Add X mana in any combination of colors, where X is the number of spells you've cast this turn.
[–3]: Create two 3/1 red Sand creature tokens with haste.

Copy target instant or sorcery spell you control. You may choose new targets for the copy.(Cast a copy of this spell once while this creature is on the battlefield.)

Rosegill Rover can't be blocked.
Whenever Rosegill Rover attacks, you may discard a card. If you do, draw a card.

At the beginning of combat on your turn, Ruination's Hand gains flying until end of turn if a creature you control or a creature card in your graveyard has flying. The same is true for first strike, double strike, deathtouch, hexproof, haste, indestructible, lifelink, menace, reach, trample, and vigilance.

Menace
Ward—Pay 3 life.
Whenever you cast a spell from anywhere other than your hand, each opponent loses 1 life and you gain 1 life.

Indestructible
Lands you control have “{T}: Add {G}{G}.”
{5}{G}{G}: Double the power and toughness of each creature you control until end of turn.

Enchant player
Creatures enchanted player controls get +0/+1.

Target creature you control gains protection from the color of your choice until end of turn. (Then exile this card. You may cast the creature later from exile.)

Flying, vigilance, lifelink
During each of your turns, you may cast a multicolored spell from your graveyard.

Target creature you control fights target creature you don't control. (Then exile this card. You may cast the creature later from exile.)

The next time one or more creatures you control would die this turn, exile those cards. You may play them until the end of your next turn.

(Transform this if it's not attached to a creature. Pay {1}{R} as a sorcery to unattach it.)
Enchant creature you control
Scale Bearer's rider gets +4/+3 and has flying and haste.
Whenever Scale Bearer's rider attacks, you may pay {2}{R}. If you do, it deals damage equal to its power to target creature or planeswalker.

Whenever Scaleblight Cutthroat attacks, each opponent loses life equal to its power.
{4}{B}{B}: Scaleblight Cutthroat gets +3/+3 until end of turn.

Enchant player
Whenever enchanted player taps a nonbasic land they control, that land doesn't untap during its controller's next untap step.

Double strike
Creatures you control have trample.
Excess noncombat damage that would be dealt by sources you control to permanents an opponent controls is dealt to that player instead.

Counter target permanent spell. (Then exile this card. You may cast the creature later from exile.)

Until end of turn, target creature gains “When this creature is dealt damage, destroy it.” (Then exile this card. You may cast the creature later from exile.)

Search your library for a basic land card, reveal it, put it into your hand, then shuffle.(Cast a copy of this spell once while this creature is on the battlefield.)

Creatures with power less than Seer of the Hunt's power can't block it.

Whenever you scry, draw a card.