msem-instigator

Raider's Den enters tapped.
{T}: Add {R}.
{R}, {T}: Target creature you control gains menace until end of turn. Activate only as a sorcery and only if you control a red creature.

Flying, first strike, haste
Whenever Doombringer Dragon attacks, you may sacrifice another creature. If you do, Doombringer Dragon gets +3/+0 until end of turn.

Armed — Beragnian Blacksmith can't attack unless it's equipped.
When Beragnian Blacksmith enters, you may pay {2}. If you do, arm it. (Create a colorless Equipment artifact token with “Equipped creature gets +1/+0” and equip {2}, then attach it to this creature.)

Whenever you draw your second card each turn, put a +1/+1 counter on Youthful Tortoise.
Cycling {2} ({2}, Discard this card: Draw a card.)

At the beginning of your upkeep, sacrifice a non-Snake creature or Boon of the Pacts. Then create a 1/1 black Snake creature token with deathtouch.
At the beginning of your draw step, draw an additional card.
Spells you cast cost {1} less to cast.

When Cloven Forms enters, reveal the top three cards of your library. Put all creature cards revealed this way into your hand and the rest into your graveyard.
{5}{G}{G}{G}, Exile Cloven Forms: Put a creature card from or hand or command zone onto the battlefield. Create a token that's a copy of it, except the token isn't legendary.

({T}: Add {W} or {B}.)
Deserted Steppe enters tapped unless you control two or more basic lands.

Whenever a creature you control enters, if it wasn't cast from your hand, you may mill a number of cards equal to its mana value. If you do, you may return a noncreature card milled this way from your graveyard to your hand.

When this enchantment enters, create a 1/1 white Peasant creature token.
{B/R}, Sacrifice a creature: Exile the top card of your library. You may play that card this turn.

{U}{R}{W}, Discard a card named Sha'Iv, God of Order: Sha'Iv gains indestructible and becomes a God creature in addition to its other types.
Whenever Sha'Iv enters or attacks, choose target creature an opponent controls. Untap it, then tap each other creature that player controls. They don't untap during their controller's next untap step.

Primal—Reappropriate green. (During your turn, you may cast this spell by exiling two green cards from your hand and/or graveyard instead of playing a land.)
When Dovon's Masterwork enters, return target land card from your graveyard to the battlefield tapped.

When Specialized Training Dummy enters, choose a card name.
Other creatures you control with the chosen name get +1/+1.

Flash
Rhapsody {5}{U}{U} (Pay {5}{U}{U} to cast this as a 4/4, or once it is in play to make it become a 4/4.)
Animus Channeler's rhapsody cost can be paid any time you could cast an instant.

Creature cards can't leave the graveyard or exile.
Players can't cast spells from graveyards or from exile.

(As an Encounter enters, choose an opponent to protect it. You and others can attack it. When defense counters are removed, create a 0/0 Army token if you don't control one, then put that many +1/+1 counters on a Army you control.)
When Settling of Kaneh enters, create two 1/1 white Soldier creature tokens if you control fewer creatures than an opponent. Then you gain 4 life if you have less life than an opponent.

Shu Qin enters with your choice of a flying or +1/+1 counter on him.
At the beginning of your upkeep, choose a creature in Shu Qin's pack. He gains that creature's abilities until end of turn. (Two or more creatures you control with equal power are in a pack.)

Destroy target attacking creature with mana value 3 or less.

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)

Flying, vigilance
Whenever you attack, if you've cast a spell from a graveyard this turn, you may pay {1}{W}. If you do, put Defender of Carü Mapu from your graveyard onto the battlefield. It's attacking.

You may have Sun Yun enter as a copy of any creature on the battlefield, except her name is Sun Yun, Master of Man, she's legendary in addition to her other types, and she has “{2}{U}: Exile Sun Yun, then return her to the battlefield under her owner's control.”

When Warrior's Perspective enters, invigorate 1. (Choose a creature with the least power among creatures you control and put a +1/+1 counter on it.)
Whenever a creature you control with a +1/+1 counter on it becomes tapped, you may draw a card. If you do, discard a card.

Enchant land
Enchanted land's name is Flowering Expanse.
Whenever enchanted land is tapped for mana, add one mana of any color.

When target creature or planeswalker dies this turn, return that card to the battlefield under your control. Destroy that permanent.

Enchant creature
Enchanted creature has base power and toughness 3/3.