msem-instigator

Humble Bridge enters tapped.
{T}: Add {R} or {W}.
When Humble Bridge enters, you may put a loyalty counter on a planeswalker you control.

Forgotten Cryovault enters tapped unless you have two or more opponents.
{T}: Add {U} or {B}.

Whenever Knight of the Verdigris deals combat damage to a player, you may sacrifice it. If you do, search your library for a green legendary creature card, reveal it, put it into your hand, then shuffle.

Mimic {2} ({2}: This takes the shape of your choice. Mimic only as a sorcery.) [3/3]
[shape 1] Flying, double strike [3/3]
[shape 2] Hexproof
{T}: Put two +1/+1 counters on Forest Dragon Telo. [3/3]

Enchant player
At the beginning of enchanted player's upkeep, they choose one —
• That player reveals their hand and discards a card.
• That player discards a card at random.

Whenever Wandering Conqueror attacks, it explores. (Reveal the top card of your library. Put it into your hand if it's a land. Otherwise, put a +1/+1 counter on this creature, then you may put that card in your graveyard.)
As Wandering Conqueror explores a land, you may put that card into your graveyard. Whenever you do, Wandering Conqueror deals 2 damage to target player or planeswalker.

Reverberate {3}{U} (When you cast this spell, copy it if you paid its reverberate cost. You may choose new targets for the copy.)
Create a token that's a copy of target creature you control.

Destroy target land. Then, judge target creature you control. (Honor it by putting a +1/+1 counter on it or condemn it by sacrificing it to draw a card.)

Archive 3 (As this enters, shuffle the top three cards of your main library into a new face up library. Sacrifice this after the archived library is empty.)
Whenever you draw a card from the archived library, target creature you control can't be blocked this turn.

Flash
When Splitting Image enters, you may pay {2} any number of times. Whenever you do, copy target spell. You may reselect modes and choose new targets for the copies.

Stinging Swordfish has first strike as long as it's attacking.
When Stinging Swordfish dies, create an Equipment enchantment artifact token named Fish Sword with “Equipped creature gets +3/+1,” “Equipped creature has first strike as long as it's attacking,” and equip {2}. You may attach that token to a creature you control.

When Ryleth, Vengeful Shadow enters, create two 1/1 green Elf creature tokens.
Whenever you attack, you may pay {1}{B/G}. When you do, return target creature card with mana value less than or equal to the number of attacking creature tokens you control from your graveyard to the battlefield tapped and attacking.

Target player discards two cards.
Flashback {4}{B} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Target creature gains lifelink until end of turn. (Damage dealt by that creature also causes you to gain that much life.)

Target creature gets +3/+3 and gains winnow until end of turn. (Damage dealt to it also causes its controller to lose that much life.)

{T}, Pay 1 life: Add {U} or {R}.
{2}, {T}, Sacrifice Lamplit Thoroughfare and another permanent: Draw a card. Activate only during your turn.

As Mysterious Cataract enters, you may pay 2 life. If you don't, Mysterious Cataract enters tapped.
{T}, Sacrifice Mysterious Cataract: Search your library for a Forest or Island card, put it onto the battlefield, then shuffle.

Flash
First strike
When Imposing Databdara enters, return each other creature with toughness less than or equal to the number of Satrapies you control to their owners' hands.

Sacrifice Moonlight Agent: Blocking creatures gain first strike until end of turn.

Heretic (Whenever you cast a spell that doesn't share a color with this creature, it gets +1/+1 until end of turn.)
{1}{B}: Lost Dancer becomes black and gains lifelink until end of turn.

Flying
As long as it's your turn, creatures you control get +3/+0 and have vigilance.
As long as it's not your turn, creatures you control get +0/+3 and have lifelink.

When Fox of the Juniper Vale enters, create an Idol token. (It's an artifact with “{1}, Sacrifice this artifact: Put a +1/+1 counter on target creature. Activate only as a sorcery.”)

({T}: Add {B}.)
Forgotten Pit enters tapped.
Deathtouch
{2}{B}{B}: Forgotten Pit becomes a creature in addition to its other types until end of turn.

Ferocious — At the beginning of each combat, if you control a creature with power 4 or greater, Impressible Cub gets +1/+1 until end of turn.