msem-instigator

Choose two —
• Counter target spell unless its controller pays {6}.
• Target player draws two cards, then discards a card.
• Creatures target player doesn't control get -3/-0 until end of turn.
• Exile up to two target creatures, then return those cards to the battlefield under their owners' control.

Hafiq the Wise has hexproof as long as you've cast a spell this turn.
{U}, Discard a card with mana value X: Counter target spell with mana value X.
{U}, Sacrifice another permanent with mana value X: Return target instant or sorcery card with mana value X from your graveyard to your hand.

At the beginning of each upkeep, choose one that hasn't been chosen —
• Exile target tapped nonland permanent.
• Draw two cards, then discard a card.
• Return up to two target permanent cards from your graveyard to your hand.
• Exile Take the City, then return it to the battlefield under your control.

Whenever Starfall Instructor attacks, harmonize. (Trigger up to one harmony of a permanent you control.)
Harmony — Each opponent loses 2 life.

Ward—Discard a card. (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player discards a card.)
You have “Ward—Discard a card.”

{U}: Enduring Rockshell gets -1/+1 until end of turn.
Whenever Enduring Rockshell perseveres, draw a card, then discard a card. (A creature perseveres when it survives damage.)

Target player puts the bottom X cards of their library into their graveyard.

Enchant creature
Whenever enchanted creature deals combat damage to a player, you may search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

This spell can't be countered.
Flying
Dominance — Whenever Stormwing Ultrateryx becomes the target of a spell an opponent controls, if you control the creature with the greatest power or tied for the greatest power, counter that spell.

Trample
Whenever a player casts a noncreature spell, that player sacrifices a noncreature permanent.

Descended Countryside enters tapped.
{T}: Add {G} or {W}.
Morph {2} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

Choose one —
• Counter target spell unless its controller pays {2}.
• Create a tapped token that's a copy of target token you control.

Vigilance, reach
Whenever Cave Spider blocks a creature with flying, Cave Spider gets +2/+0 until end of turn.

Up to one target creature you control has base power 4 until end of turn. (Then exile this card. You may play the land later from exile.)

Primal {1}{G}{G} (During your turn, you may cast this spell for {1}{G}{G} instead of playing a land.)
When Orria's Ward enters, if you played a land this turn, draw a card. Otherwise, put two +1/+1 counters on it.

Flying, haste
Whenever Epoch Warden attacks, you may aetherize another target attacking creature you control. (To aetherize, create a token that's a copy of it, then exile that token.)

Menace
Whenever a land enters, you may search its controller's library for up to three land cards with the same name as that card, put them into that player's graveyard, then that player shuffles.

Equipped creature has hexproof and improve {1}. ({1}: Put a +1/+1 counter on that creature. This costs {1} more to activate for each +1/+1 counter on it. Improve only as a sorcery.)
{4}: Put Faithforged Pauldron from your hand onto the battlefield attached to target creature.
Equip {1}

Create a 2/2 white Angel creature token with flying.
Coalesce {6}{W}{W} (You may cast this from your graveyard for {6}{W}{W}. If you do, it enters as a Horror creature after it resolves. Exile it if it would leave the battlefield or not resolve.)
Flying

When Expedition Outfitter enters, create a 1/1 colorless Servo artifact creature token.
At the beginning of each end step, if an artifact was put into your graveyard from the battlefield this turn, Expedition Outfitter deals 1 damage to each opponent.

Vanishing 3 (This creature enters with three time counters on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)
When Hapless Chronomancer dies, if it had no time counters on it, return target instant or sorcery card from your graveyard to your hand.

As Scrolls of Succession enters, choose a creature type.
Creatures you control of the chosen type get +1/+1.
{2}, {T}: Draw a card. Then discard a card unless you control three or more creatures of the chosen type.

Creatures you control get +2/+0.
Whenever a creature you control is dealt damage, it deals that much damage to you.

({T}: Add {W} or {U}.)
As Lakeside Park enters, you may pay {1}. If you don't, Lakeside Park enters tapped.

Target creature you control gains lifelink until end of turn. Arm it. (Create a colorless Equipment artifact token with “Equipped creature gets +1/+0” and equip {2}, then attach it to that creature.)