msem-instigator

All creatures able to block Osheen Courtier do so.
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.)

Vigilance
Tribute 3 (As this creature enters, an opponent of your choice may put three +1/+1 counters on it.)
When Dignified Serpent enters, if tribute wasn't paid, put a +1/+1 counter on each other creature you control.

Flying, haste
Ward—Pay 3 life.
The first Dragon spell you cast each turn costs {R}{R} less to cast. (This can reduce the amount of generic mana you pay.)

Whenever Merchant of Flesh or another creature you control dies, create a Treasure token. (It's an artifact with “{T}, Sacrifice this artifact: Add one mana of any color.”)
{B}, Sacrifice two Treasures: Each opponent sacrifices a creature.

Reach
When this creature dies, create a 1/1 red Dwarf creature token.

Delusional Noble enters with a -1/-1 counter on it.

Pyrostorm deals 10 damage divided as you choose among any number of targets.

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

Prowess, haste
Whenever you cast an instant or sorcery spell, you may shuffle the cards in your hand into your library, then draw that many cards.

{1}{U}, {T}: Reveal the top card of your library. If it doesn't share a color with Heretical Seer, put it into your hand.

Sacrifice a creature: Exile the top card of your library. Until end of turn, you may play that card.

Tap target creature. If you control a Monk, draw a card. (Then exile this card. You may cast the creature later from exile.)

When Marionette Phantom enters, choose one —
• Draw a card.
• Proliferate. (Choose any number of permanents and/or players with counters on them, then give each another counter of each kind already there.)

Dawn Hill Outskirts enters tapped unless you played it from exile.
{T}: Add {R} or {W}.

Whenever you cast a legendary spell, each opponent loses 1 life and you gain 1 life.
{W}{B}, Sacrifice a legendary nonland permanent: Draw two cards.

Target creature gets +2/+2 and gains indestructible until end of turn.

Destroy target planeswalker. Mummy's Grin deals 2 damage to that planeswalker's controller.

Exile target creature or planeswalker. Its controller may search their library for a creature or planeswalker card and reveal it, then shuffle and put that card on top.

Regenerate target creature. (The next time that creature would be destroyed this turn, it isn't. Instead tap it.)

At the beginning of your end step, if you cast no spells this turn, untap target creature.

Target creature can't be blocked this turn.
Proliferate. (Choose any number of permanents and/or players with counters on them, then give each another counter of each kind already there.)

As an additional cost to cast this spell, you may discard a card. If you do, this spell costs {4} less to cast.
Total Process Failure deals 5 damage to target creature or planeswalker. If that creature or planeswalker would die this turn, exile it instead.

Warm Blood Chaser has flying and haste as long as you control a Goblin.

Haste
Sacrifice another creature: Bygone Aristocrat gains indestructible until end of turn.

Flash
Flying
When Oshin enters, counter target spell if its mana value is less than or equal to the number of spells you've cast this turn.