msem-instigator

Destroy target creature or planeswalker.
Agonize (You may cast this card from your graveyard by putting a -1/-1 counter on a creature you control in addition to paying its other costs. Then exile this card.)

Tap up to three target lands. They don't untap during their controller's next untap step.
Agonize (You may cast this card from your graveyard by putting a -1/-1 counter on a creature you control in addition to paying its other costs. Then exile this card.)

Flash

Breach (Whenever this deals combat damage to a player, you may have it become an Aura Curse until your next turn. Attach it to that player.)
At the beginning of your end step, if an opponent is cursed, surveil 2.

Whenever another creature or enchantment you control enters, you gain 1 life.
{3}{W}{W}, Pay 5 life: Castigated Sister becomes a 5/5 Angel Horror with flying. (This effect doesn't end at end of turn.)

Treacherous Oasis enters tapped.
{T}: Add {U} or {B}.
{2}{U}{B}: Until end of turn, Treacherous Oasis becomes a Crocodile creature in addition to its other types. It can't be blocked this turn.
Scavenge {1}{U}{B}

As an additional cost to cast this spell, sacrifice a creature.
Search your library, hand, or graveyard for a creature card with mana value 1 greater than the sacrificed creature's and put it onto the battlefield. If you searched your library this way, shuffle.

Enchant creature
When enchanted creature dies, you draw X cards, where X is its toughness. Then you may put a land card from your hand onto the battlefield.

Whenever Angeltouched Komodo attacks, scry 1.
Morph {1}{R} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

{T}, Sacrifice a Snake: Choose a counter on target permanent or player. You may put an additional counter of that kind on that permanent or player.

[+1]: Creatures you control get +0/+1 until your next upkeep. Untap those creatures.
[–2]: Put target tapped creature into its owner's library third from the top.
[–7]: You get an emblem with “Whenever a nonland permanent you control is put into a graveyard from the battlefield, each opponent sacrifices a nonland permanent.”

Whenever a -1/-1 counter is put on a creature, you may create a 1/2 green Frog creature token.

Menace
At the beginning of your upkeep, you may pay 3 life. If you do, draw a card.

When Arcanomancer enters, return up to one target instant card and up to one target sorcery card from your graveyard to your hand.

For each creature you control, create a token that's a copy of it. They gain haste. Sacrifice them at the beginning of the next end step.

Rhapsody {4}{U}{U} (Pay {4}{U}{U} to cast this as a 4/4, or as a sorcery to make it become a 4/4.)
When Unstable Prophet enters, surveil X, where X is its power. (Look at the top X cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)

Unbound Spirit can't be blocked.
When you attain Unbound Spirit, tap target creature. That creature doesn't untap during its controller's next untap step.

Alpha (You may have this creature enter with a +1/+1 counter on it. If you do, it becomes alpha and can only attack alone.)
Whenever a creature you control attacks alone, untap all lands you control.

When Hand of Consequence enters, creatures your opponents control get -1/-1 until end of turn.
At the beginning of your upkeep, if your fealty to Swamps is five or greater, transform Hand of Consequence. (Each Swamp you control counts towards your fealty to Swamps.)

Destroy all creatures with mana value 3 or less.

Whenever this creature enters, attacks, or leaves the battlefield, choose one that hasn't been chosen.
• Return another target nonland permanent to its owner's hand.
• Draw two cards.
• Create three 1/1 blue Bird creature tokens with flying.
• Add {U}{U}{U}{U}. You can't spend this mana to cast creature spells.

As Ancestral Facsimile enters, choose reality or illusion.
Foresight — Whenever you draw your second card each turn,
• Reality — Tap target creature.
• Illusion — Scry 2.

When Kwende Peak Partisan enters, exile the top card of your library. If it's a land card, you may play it this turn.

Archive X, where X is the number of planeswalkers you control. (As this enters, shuffle the top X cards of your main library into a new face up library. Sacrifice this when the archived library is empty.)
Remove a loyalty counter from a planeswalker you control: Draw a card from the archived library.