msem-instigator

This spell costs {1} less to cast for each creature that attacked this turn.
Hot to the Touch deals X damage to any target.

For any number of permanent types, you may exchange control of two target permanents that share that type.

Whenever you discard a card this turn, add {B}. Then you may cast that card. (You still pay its costs.)

Trample
When Stensia Cavalcade enters, create two Weapon tokens. (They're Equipment artifacts with “Equipped creature gets +1/+1” and equip {2}.)

Look at the top five cards of your library. You may reveal a nonland card from among them. If you do, put that card into your hand and cast a copy of it without paying its mana cost. Put the rest into your graveyard.

When Artillery Mage enters, it deals 5 damage to target creature you don't control.
{5}{R}, {T}, Discard a card: Artillery Mage deals 5 damage to target creature you don't control.

{G}, Discard a noncreature card: Reveal the top five cards of your library. You may put a creature card with mana value X or less from among them into your hand, where X is the discarded card's mana value plus one. Put the rest on the bottom of your library in any order.

Enchant opponent
Whenever enchanted player draws a card or casts a spell, put a foreshadow counter on Thalassophobia.
Remove eight foreshadow counters from Thalassophobia and sacrifice it: Create an 8/8 blue Kraken creature token.

Bloodfell Caves enters tapped.
When Bloodfell Caves enters, you gain 1 life.
{T}: Add {B} or {R}.

Destroy target creature. If you do, you may put a +1/+1 counter on a creature you control.

Flying
Whenever you tap a Mountain for mana, add {R} and that land deals 1 damage to you.
Whenever you tap a non-Mountain land for mana, that land deals 1 damage to Tseng, Warden of the Peak.

Each other Okus planeswalker you control enters with two additional loyalty counters on it.
[–2]: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

When Blighting Ooze enters, put a -1/-1 counter on each of up to X target creatures.
As long as Blighting Ooze is on the battlefield, it has all activated abilities of each creature with a -1/-1 counter on it.

When Mourners of Mervin enters, you may sacrifice a creature or enchantment. If you do, creatures you control get +1/+1 and gain vigilance until end of turn.

{1}: Danaj Sightseer gains lifelink until end of turn if {W} was spent to activate this ability. The same is true for flying and {U}, menace and {B}, first strike and {R}, and trample and {G}.
At the beginning of your end step, if you've spent {W}{U}{B}{R}{G} to cast spells and/or activate abilities this turn, put three +1/+1 counters on Danaj Sightseer.

Charbroiled Core enters tapped unless you have two or more opponents.
{T}: Add {B} or {R}.

Heretic (Whenever you cast a spell that doesn't share a color with this creature, it gets +1/+1 until end of turn.)
Whenever you cast a white, blue, black, or red spell, add one mana of any color that spell isn't.

Target creature gets +1/+0 until end of turn. Add {R}.

Whenever a creature enters, you may tap it. If you do, put a +1/+1 counter on it.

Sleight (You may cast this spell as though it had flash if you pay {1} more to cast it.)
Search your library for a green creature card with mana value X or less, put it onto the battlefield, then shuffle.

Whenever you gain life, target opponent loses that much life.
{T}, Pay 3 life: Flip a coin. If you win the flip, you gain 6 life.

When Lay Bare Ambitions enters, if it was cast, target opponent reveals their hand. Choose a nonland card from it. That player discards that card.
If a spell or ability an opponent controls would cause them to draw one or more cards, instead sacrifice Lay Bare Ambitions and they skip those draws.

Whenever you activate one of Ai's loyalty abilities, create a 2/2 colorless Soldier artifact creature token with that ability, except it costs +1 to activate.
[+1]: Ai deals 1 damage to target player or planeswalker. You gain 1 life.
[–3]: Draw a card. You lose 1 life.
[–7]: Each opponent sacrifices a permanent and discards a card.

Bulwark — If you control a creature with toughness 4 or greater, each creature you control assigns combat damage equal to its toughness rather than its power this turn.
Creatures you control get +0/+2 until end of turn.

This spell costs {1} less to cast for each time you catalyzed this turn.
Counter target spell unless its controller pays {X}.