msem-instigator

Enchant creature
Enchanted creature gets +2/+2.
When Seeking Horizons is put into your graveyard from anywhere other than your library, investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

{T}: Add {C}.
{4}, {T}: Look at the top two cards of your library. You may put one of them into your graveyard. Put the rest back on top in any order. If you control eight or more lands, draw a card.

Trample
{4}{G}: Centaur Warband gets +2/+2 until end of turn.

Menagerie — When Paw Valley Alpha enters, if there are five or more creature types among creatures you control, you may destroy target artifact or enchantment.

When you cast your third noncreature spell each turn, transform Aspiring Rascals.

This spell can't be countered.
Destroy target nonbasic permanent.

[+1]: Until your next upkeep, creatures can't attack you or planeswalkers you control unless their controller pays {2} for each of those creatures.
[–2]: Look at the top two cards of target player's library. Put any number of them on top of that library and the rest on the bottom in any order.
[–6]: Return all nonland permanents you don't control to their owners' hands.

Target player sacrifices a creature. If you control an artifact, draw a card.

Choose one —
• Draw three cards.
• Return up to two target creatures to their owners' hands.

As long as you control exactly two creatures, those creatures get +2/+1 and have lifelink.

When Gilded Yak enters, you gain 3 life.

Encourage ({T}: Another target creature you control gets +1/+1 until end of turn. Encourage only as a sorcery.)
Whenever Paladin's Attendant encourages a creature, that creature gains first strike until end of turn.

({T}: Add {G} or {U}.)
Whenever Shifting Glade becomes tapped, you lose 1 life unless you control two or more basic lands.

When Vespercloak Vampire dies, create a 1/1 black Bat creature token with flying and lifelink.
Foreshadow {3}{B} (You may cast this spell for its foreshadow cost. If you do, also trigger its “dies” abilities when it enters.)

Melodae, the Favored can't be blocked by black creatures.
If Melodae would be destroyed, instead sacrifice a creature and Melodae gains indestructible until end of turn.

Target player draws a card for each card in their graveyard.

Trample
Tribute 3 (As this creature enters, an opponent of your choice may put three +1/+1 counters on it.)
When Rockpounding Saurian enters, if tribute wasn't paid, you may destroy up to one target artifact, up to one target land and up to one target Fortress.

Ode to the Red Wind deals 1 damage to target creature. It can't block this turn.
Showcase {3}{R} (Then if you cast this for its showcase cost, create a 1/1 red Bard creature token that can't block and exile this. Whenever it attacks, you may cast a free copy of this.)

Create a number of 3/3 green Elemental creature tokens equal to the number of differently named lands you control.
Fuse (You may cast one or both halves of this card from your hand.)

Create a 1/1 white Spirit creature token with flying. (Then exile this card. You may cast the artifact later from exile.)

{U}, Sacrifice a creature: Discard a card, then draw a card.

Indestructible
As long as your devotion to blue is less than five, Thassa isn't a creature.
At the beginning of each combat, you may tap or untap another target nonland permanent.
{2}{U}: Create a 1/1 blue Merfolk Rogue creature token with “{T}: Draw a card, then discard a card.”

Target creature and all creatures with the same name as that creature get +2/+1 and gain lifelink until end of turn.

When El, Humble Apprentice enters, search your library for a basic land card, reveal it, put it into your hand, then shuffle.
Chosen one ({W}{U}{B}{R}{G}: Transform this permanent.)

When Host of Nature enters, create two 2/2 red and green Elk creature tokens.