msem-instigator

Flying
When Aven Strategist enters, return up to one target creature to its owner's hand.

Flying, haste
Assault {1}{R} (Whenever this attacks, if it has no +1/+1 counters on it, you may pay its assault cost to put a +1/+1 counter on it.)
Whenever one or more +1/+1 counters are put on a creature you control, you may return Sunnula's Firebird from your graveyard to your hand.

Enchant creature
When Kalku Initiation enters, you lose 3 life and discard a card.
Enchanted creature gets +3/+2, has ward {2}, and has “Whenever this creature deals damage to a player, draw two cards.”

Return all creature cards from your graveyard to the battlefield, then exile all but one of them.

Whenever Knight of the Verdigris deals combat damage to a player, you may sacrifice it. If you do, search your library for a green legendary creature card, reveal it, put it into your hand, then shuffle.

Whenever a Survivor you control dies, target creature you don't control gets -1/-1 until end of turn.

Enchant opponent
At the beginning of enchanted player's upkeep, they mill two cards.
{U}, Sacrifice Strange Tides: Shuffle up to four target cards from your graveyard into your library.

Deploy 2 (As this enters, you may tap any number of other creatures you control with total power 2 or more.)
When Parish Infantry enters deployed, search your library for a card named Parish Infantry, reveal it, put it into your hand, then shuffle.

Exile two target creatures, planeswalkers and/or enchantments, then return one of those cards to the battlefield under its owner's control.

Look at the top four cards of your library. You may put a land card from among them onto the battlefield tapped, then put the rest into your graveyard.

Destroy target tapped creature, then untap all creatures you control.

Flying
When Foul Drifter enters, target creature gets -1/-1 until end of turn.

Flash
When Tenvilu, Earthen Warden enters, other creatures you control get +2/+2 and gain hexproof and indestructible until end of turn.

Civilized — Adorned Naga gets +2/+0 and has menace as long as you control an artifact, a creature, and an enchantment.

{T}: Add {C}.
Tap three differently named untapped Academies you control: Put a +1/+1 counter on target permanent. Activate only as a sorcery.

Whenever a creature you control dies, put a soul counter on Hill of Souls.
{T}: Add {C}.
{T}, Remove a soul counter from Hill of Souls: Add one mana of any color.

Whenever Arena Challenger deals damage to a creature, upgrade it. (Give it one of the listed counters it doesn't already have.)
• +1/+1
• First strike
• Prowess

Flying, vigilance
At the beginning of your upkeep, if you have 10 or more life than your starting life total, put a +1/+1 counter on each other creature you control.

When Beguiling Witch enters, nourish 1. (To nourish 1, either put a +1/+1 counter on this creature or create a 1/1 white Citizen creature token.)
Whenever another creature dies, each opponent mills X cards, where X is Beguiling Witch's power.

({T}: Add {B} or {G}.)
As Ruptured Morass enters, you may pay {1}. If you don't, Ruptured Morass enters tapped.

Flying
Whenever another creature you control attacks, you may pay {1}. If you do, put a +1/+1 counter on it.

Whenever Ore Tunneler deals damage to an opponent, tap target land they control. It doesn't untap during its controller's next untap step.

As an additional cost to cast this spell, return a creature you control to its owner's hand.
You may put a creature card with mana value less than or equal to the returned creature's mana value from your hand onto the battlefield with a +1/+1 counter on it.

Enspirit (As you cast this spell, you may exile a nonenchantment creature you control until this leaves the battlefield or fails to resolve. Reduce this spell's cost by the exiled card's mana value.)
{T}: The next creature spell you cast this turn has enspirit. When that creature enters, it becomes an enchantment in addition to its other types.

When Masha's Lightbound becomes tapped for the first time each turn, untap Masha's Lightbound and each other creature you control.
{W}, {T}: Exile target card from a graveyard.