msem-instigator

Whenever Harvester of Secrets or another creature enters from your graveyard, you may draw a card.
Unearth {2}{U}{B} ({2}{U}{B}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the end step or if it would leave the battlefield. Unearth only as a sorcery.)

When Fang of Andazir enters, each player sacrifices a permanent.
Whenever you sacrifice a creature for the first time each turn, create a 1/1 red Dog creature token.

{B}{R}, {T}, Sacrifice Heretical Soulshifter: Return target creature card from your graveyard to the battlefield. It gains haste until end of turn. Activate only as a sorcery.

If a spell or ability an opponent controls causes you to discard Edgar, put it onto the battlefield instead of putting it into your graveyard.
Unveil {4}{G}{W} ({4}{G}{W}: Transform this. Unveil only as a sorcery.)

Motivate 2 (When this creature enters, you may motivate target creature with less power than this by putting two +1/+1 counters on it.)
Whenever a creature you control becomes motivated, you gain 2 life.

{W}{B}, Shuffle Inexorable Explorer into your library: Return target creature card from your graveyard to the battlefield.
{W}{B}, Sacrifice a creature: Return Inexorable Explorer from your graveyard to the battlefield tapped.

When Long Lost Cause enters, each opponent exiles a card from their hand or a creature they control.

Vigilance
When this creature dies, target creature you control seeks secrets or valor. (Give it that Oath Aura. Fulfill secrets by attacking with it and two or more other creatures to draw a card. Fulfill valor by dealing combat damage to a player to create a 2/1 white Soldier token.)

Hexproof
Whenever Twinning Psionic harnesses an instant or sorcery spell, you may copy that spell. If you do, you may choose new targets for the copy.

When Heedless Lovers enters, you may return target Citizen card from your graveyard to your hand.
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 Quillback dies, you may shuffle him into his owner's library. If you do, return up to one target Shaman creature card and up to one target non-Shaman creature card from your graveyard to your hand.

Flash
When Outland Alchemist enters, return another permanent you control to its owner's hand.

Menace, haste
Whenever Manic River-Fishers attacks, you may search defending player's library for an instant or sorcery card that shares a name with a card in their graveyard and cast it without paying its mana cost. That player shuffles.

When Lysander Jal enters, create a token that's a copy of another target noncreature permanent you control.
Whenever you cast a spell from your graveyard, return target permanent card from your graveyard to your hand.

Flying

Menace
Crew 2 (Tap any number of creatures you control with total power 2 or greater: This Vehicle becomes an artifact creature until end of turn.)

Flying, lifelink
Golden age (If you cast an instant or sorcery spell, activated a nonmana ability, and attacked this turn, enter a renaissance for this game.)
You may cast this card from your graveyard as long as you're in a renaissance.

Flying, vigilance
Augmented — When Antigravity Agent enters, if you've spent {W}{U}{R}{B}{G} to cast spells this turn, distribute a flying counter and a vigilance counter among one or two creatures you control.

Reach
As Celestial Principality enters, choose a number.
Noncreature spells with mana value equal to the chosen number can't be cast.

Flying (This creature can't be blocked except by creatures with flying or reach.)
Whenever a creature you don't control blocks, it gets -1/-0 until end of turn.

Vigilance
Melee (Whenever this creature attacks, it gets +1/+1 until end of turn for each opponent you attacked this combat.)
Whenever an opponent attacks you, create a tapped 1/1 white Soldier creature token with melee. Exile that token at the beginning of your next end step.

When Haughty Paladin enters, you may sacrifice another artifact or creature. If you do, tap all creatures your opponents control.

Flying
Whenever Hecatomb Haunter enters or attacks, up to one other target nonland permanent phases out. (Treat it and anything attached to it as though they don't exist until its controller's next turn.)

Flying
When this creature enters, return target creature card with flying from your graveyard to your hand.

While an opponent is choosing targets as part of casting a spell they control or activating an ability they control, that player must choose at least one Flagbearer on the battlefield if able.
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.)