msem-instigator

Flying
Whenever Albino Drake deals combat damage to an opponent, create an Idol token. (It's an artifact with “{1}, Sacrifice this artifact: Put a +1/+1 counter on target creature. Activate only as a sorcery.”)

When Allagras' Vanguard enters, create two 1/1 blue Merfolk creature tokens with “When this creature dies, draw a card, then discard a card”.

Whenever Arisen Helix attacks, scry 2.
If Arisen Helix would die, exile it instead.

When Azure Archaeologist enters, investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)
{2}, {T}, Sacrifice a Clue: Draw two cards, then discard a card.

When Banished Prophet enters, you may remove a counter from a permanent you control. If you do, put a +1/+1 counter on another target creature you control.

When Boneweary Warrior dies, you may put a -1/-1 counter on target creature.

Breezerider has flying as long as you control a Nymph.
Breezerider has hexproof as long as you control another Monkey.

Flash
When Brightsouled Guardian enters, return up to one target nonland permanent to its owner's hand.

Whenever you draw a card, you may have target player mill two cards.

Flash
Harmony — You may tap or untap target creature.
When Captivating Jester enters, harmonize. (Trigger up to one harmony of one permanent you control.)

Flash (You may cast this spell any time you could cast an instant.)
Flying
Tapped creatures you control have hexproof.

Whenever you cast a spell, reveal the top card of your library. If a card that shares a card type with that spell was revealed this way, Chaos Tradewinder gains flying until end of turn.

Flying
{3}{R}, {T}: Cloudwing deals 2 damage to target creature. You may tap or untap that creature.

Ward {2} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.)
Attain {4}{U} ({4}{U}: Transform this. Spend at least three colors of mana to activate this, and only as a sorcery.)

Pressure {1}{U} (You may cast this spell for its pressure cost if seven or more cards are in your graveyard.)
When Cuxuri Harbinger enters, draw a card.

Breach (Whenever this deals combat damage to a player, you may have it become an Aura Curse until your next turn. Attach it to that player.)
Whenever a cursed opponent attacks, you may draw a card.

At the beginning of your end step, if you have no cards in hand, draw a card.
{2}{U}, {T}: Sacrifice any number of nontoken creatures. Create an X/X blue Horror creature token for each of those creatures, where X is the total power of those creatures.

Flying (This creature can't be blocked except by creatures with flying or reach.)
When Drake Youngling enters, draw a card.

Whenever Chian becomes the target of a spell or ability you control, create a 2/2 blue Drake creature token with flying. This ability triggers only once each turn.

Flash
{U}, Put Elusive Hunter into its owner's library second from the top: Counter up to one target spell unless its controller pays {2}.

{1}: Target Equipment becomes a colorless 3/3 Construct artifact creature until end of turn. (Equipment that's a creature can't equip a creature.)
{2}{U}{U}, {T}: Return target artifact card from your graveyard to your hand.

Inspired — Whenever Festival Decorator becomes untapped, draw a card.

Flying
Whenever you cast a spell with mana value 4 or greater, sacrifice Fractured Prodigy. If you do, create two tokens that are copies of Fractured Prodigy.

Flying
Instant, sorcery, and Wizard spells you cast cost {1} less to cast.