msem-instigator

When Memory Figment is put into your graveyard from your hand or library, you may exile it. If you do, for as long as it remains exiled, you may cast it. It costs {2} less to cast this way.

{1}{U}: Mercurial Merfolk gets +2/-2 until end of turn.
When Mercurial Merfolk dies, draw a card.

Flying
If Mindbreaker Sphinx would deal combat damage to a player, you may prevent it. If you do, that player mills X cards, where X is Mindbreaker Sphinx's power. If two cards that share a card type were milled this way, put a +1/+1 counter on Mindbreaker Sphinx.

Other Spirits you control get +1/+1.
Whenever Mistmourner or another Spirit you control enters, you may draw a card. If you do, discard a card.

Flash
Whenever Moonlit Hunter enters or you cast a noncreature spell, tap target permanent and untap a second target permanent.

{B}{G}{U}: Mother Roo gets +2/+2 and gains flying until end of turn.

Flying
Whenever Naiala's Guide deals combat damage to a player, draw a card, then discard a card.

Chronicle (As this enters and after your draw step, add a lore counter. Stop after III.)
[Lore I-II] Tap target creature you don't control.
[Lore III] Tap target creature you don't control. It doesn't untap during its controller's next untap step.

Flying
At the beginning of your end step, up to one other target creature you control voyages. (If it isn't blocking or targeted by another spell or ability, it phases out.)
Whenever a creature you control phases in, you may have it become a copy of target creature you control until end of turn.

Whenever Orria Mirrorpelt becomes the target of a spell, exile that spell. If Orria Mirrorpelt was its only target, copy it for each other creature target player controls. Each copy targets a different one of those creatures.

Flash
Flying
When P05 Suppressor enters, create a Function token with “Tap target creature. Put a stun counter on it.” (It's an enchantment. As you cast an instant or sorcery spell, sacrifice any number of Functions to add their effects to that spell.)

Flash
Flying
Whenever you cast another spell with flash or an instant, put a stun counter on up to one target creature if it's tapped. Otherwise, tap it.

When Paralysis Specialist enters, up to two target creatures don't untap during their controller's next untap step.

Whenever a Monkey creature you control becomes the target of a spell or ability, you may reveal the top card of your library. If you do, counter that spell or ability if it has the same mana value as the revealed card. (Abilities have a mana value of 0.)

Flying, ward {2}
Whenever Realm Crossers deals combat damage to a player, create a blue enchantment token named Tambo with “At the beginning of your upkeep, draw a card if you control a Scout.”

Embellish {5}{U} (If you cast this spell for {5}{U}, create a 1/1 blue Thopter artifact creature token with flying when it enters.)
Retinue Golem gets +1/+1 as long as you control another artifact.

{U}, {T}: You may tap or untap another target creature.
Whenever one or more other creatures you control deal combat damage to a player, you may untap Riverchase Diver.

Harmony — Untap target permanent.
Whenever you cast an instant or sorcery spell, harmonize. (Trigger up to one harmony of one permanent you control.)

When Runebreaker Mage enters, return another target nonland permanent you control and target nonland permanent you don't control to their owner's hands.

{U}: Sea Strider gets +1/-1 until end of turn.
{U}: Sea Strider gets -1/+1 until end of turn.

Defender (This creature can't attack.)
Whenever you cast a spell, if it isn't your main phase, Serene Meditant loses defender until the beginning of your next end step.

Flying
When Sharp-Eyed Wingmate enters, you may return target creature to its owner's hand.

Whenever a player casts an instant or sorcery spell from their hand, you may exile that card as it resolves instead of putting it anywhere else.
Whenever Skill Sketcher attacks, you may cast a card exiled with it. That spell costs {X} less to cast, where X is Skill Sketcher's power.

{1}{U}: Skysail Rigger voyages. (If it isn't blocking or targeted by another spell or ability, it phases out.)
Whenever Skysail Rigger phases in, put a flying counter on it.

Whenever Skysworn Savior attacks, you may return another creature you control to its owner's hand. If you do, Skysworn Savior gets +2/+2 and gains flying until end of turn.