msem-instigator

When a creature you control scavenges Harvest Reaper, search your library for a colorless card, reveal it, put it into your hand, then shuffle.
Scavenge {4} ({4}, Exile this card from your graveyard: Put a number of +1/+1 counters equal to this card's power on target creature. Scavenge only as a sorcery.)

When Ethereal Spellmaster enters, if it was cast, you may search your library for an instant or sorcery card with mana value 3 or less and cast it without paying its mana cost. If you do, shuffle your library. (If it has X in its mana cost, X is 0.)

Shimmer (Whenever this creature attacks, create a tapped and attacking token that's a copy of it. Exile the token at the beginning of the end step.)

Each other Rogue creature you control enters with an additional +1/+1 counter on it.
Remove a +1/+1 counter from a creature you control: That creature can't be blocked this turn.

When Chronomancer Adept enters, put a time counter on each permanent you control with a time counter on it.
Whenever a permanent with vanishing you control leaves the battlefield, you may draw a card.

Whenever you cast a noncreature spell, any number of target creatures you control get +1/+1 until end of turn.
Whenever a creature you control deals an amount of combat damage exactly equal to its mana value to a player or planeswalker, draw a card.

When Sunset Monastery enters, draw a card, then put a card from your hand on the bottom of your library.
{T}: Add {C}.

Flying
Whenever Prismatic Scyphozoa attacks or blocks, target player mills three cards.
When Prismatic Scyphozoa dies, create four 1/1 blue Elemental creature tokens with flying.

When Fiend of Convenience enters, destroy target creature an opponent controls.
Whenever Fiend of Convenience attacks, each opponent loses 3 life.

When Silencing Guardian enters, you may have target creature get -1/-1 until end of turn.

As Floodwater Depths enters, you may pay 2 life. If you don't, Floodwater Depths enters tapped.
{T}, Sacrifice Floodwater Depths: Search your library for an Island or Swamp card, put it onto the battlefield, then shuffle.

When Old Salt enters, forebode. (Create a tapped colorless Omen artifact token with “{T}, Discard a card, Sacrifice this artifact: Draw a card.”)

Search your library for a permanent card with mana value X or less, reveal it, put it into your hand, then shuffle.

Mortalcoil Hydra enters with a number of +1/+1 counters on it equal to the amount of mana spent to cast it.
When Mortalcoil Hydra dies, each opponent loses 3 life and you gain 3 life.
Foreshadow {4}{B}{G} (You may cast this spell for its foreshadow cost. If you do, also trigger its “dies” abilities when it enters.)

This spell can't be countered.
Trample
Whenever Lumbering Thoctar becomes the target of a spell or ability, counter it. Then put a stun counter on Lumbering Thoctar.
Whenever Lumbering Thoctar becomes untapped, draw a card.

Flying
Whenever Theurgic Flock deals combat damage to a player, if it doesn't have a +1/+1 counter on it, put a +1/+1 counter on it.

{T}, Sacrifice a creature: Conjure a card named Data-Point into your hand. Activate only as a sorcery. (It's a sorcery that costs {2} with “Draw a card.”)

Put target attacking or blocking creature on the bottom of its owner's library.

Enchant creature
When Bogfume Pact enters, each opponent sacrifices a creature.
When enchanted creature dies, return it to its owner's hand.

You may reveal a creature card with flying you own from outside the game and put it into your hand. Exile Snag Apparition.

When River Miscreants enters, target creature you control can't be blocked this turn.
{2}{U}: Return River Miscreants to its owner's hand. Activate only as a sorcery.

Target creature gets +X/+X and gains vigilance until your next turn, where X is the number of creatures you control.

Destroy target artifact or enchantment. You gain 2 life.

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Infiltrate (Whenever one or more attacking creatures you control aren't blocked, this creature gets +1/+1 until end of turn.)

Create a 1/1 blue Faerie Rogue creature token with flying. Scry 2.