msem-instigator

Whenever another creature you control enters, if its power is greater than Scalebruiser's power, put a +1/+1 counter on Scalebruiser.
As long as Scalebruiser's power is 4 or greater, each other creature you control enters with an additional +1/+1 counter on it.

Tap up to two target creatures. Those creatures don't untap during their controller's next untap step.
Menagerie — If there are five or more creature types among creatures you control, scry 3.

Counter target spell with no subtypes. Surveil 1. (Look at the top card of your library. You may put that card into your graveyard.)

Scoundreleo enters with a +1/+1 counter on it if a creature you controlled dealt combat damage to a player this turn.

Scoured Mesa enters tapped.
{T}: Add {W}.
Desertcycling {1}{W} ({1}{W}, Discard this card: Search your library for a Desert card, reveal it, and put it into your hand, then shuffle.)

As an additional cost to cast this spell, pay 3 life and sacrifice a creature.

Menace
Sacrifice another artifact: Scrap Buggy becomes an artifact creature until end of turn.
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.)

Counter target permanent spell. (Then exile this card. You may cast the creature later from exile.)

Ward {2}
Once each turn, if you would create one or more tokens, create that many of those tokens plus one instead.

Flying
Whenever you cast a creature spell, if Script Spirit is in your graveyard, you may have it become a copy of that spell until end of turn.

At the beginning of combat on your turn, if you cast both a creature spell and a noncreature spell this turn, untap up to one target land you control. It becomes a 3/1 red Sand creature with haste in addition to its other types until end of turn.

Until end of turn, target creature gains “When this creature is dealt damage, destroy it.” (Then exile this card. You may cast the creature later from exile.)

Take an extra turn after this one. During that extra turn, you may cast spells you own not named See the World from outside the game by tapping an untapped Scout you control in addition to paying their mana costs.
Exile See the World.

(Add a quest counter as this enters. Sacrifice after 3.)
Whenever a land you control enters, add a quest counter.
Create a 1/1 Scout creature token that's all colors.
Creatures you control get +2/+1 until end of turn.
Creatures you control get +1/+1 until end of turn.

Glorious end — When Seeker of Conto Sika dies, if it was tapped, draw a card.

Mill five cards, then you may exile any number of cards from your graveyard. Create an X/X black Horror creature token with menace, where X is the number of cards exiled in this way. (To mill five cards, put five cards from the top of your library into your graveyard.)

Return up to one target creature you control and up to one target creature you don't control to their owners' hands.

Equipped creature gets +2/+0. As long as it's a Knight, it has first strike.
Equip {1}{W}

Defender (This creature can't attack.)
Whenever you cast a spell, if it isn't your main phase, Serene Meditant loses defender until the beginning of your next end step.

Flash
Menagerie — When Seven Seas Scourge enters, if there are five or more creature types among creatures you control, counter target spell with mana value 4 or less.

When Shaman of Burning Ashes enters, return target instant or sorcery card from your graveyard to your hand. When you do, each opponent loses X life, where X is that card's mana value.

Concord — {T}: Tap target nonland permanent. Activate only if there are four or more card types among permanents you control.

Kicker—Return a creature you control to its owner's hand. (You may return a creature you control to its owner's hand in addition to any other costs as you cast this spell.)
Counter target spell. If Shinrei's Ruse was kicked, draw a card.

Flying
Instant and sorcery spells you cast cost {1} less to cast.
Whenever you cast your second spell each turn, draw a card.

Search your library for two basic land cards, reveal them, put them into your hand, then shuffle. (Then exile this card. You may cast the creature later from exile.)