msem-instigator

Mark (Whenever this creature attacks, mark target creature until end of turn.)
Alley Hunter has lifelink as long as it's blocked by a marked creature.

Sacrifice Amateur Auteur: Destroy target enchantment.

You may activate abilities of nonland permanents your opponents control.

This spell costs {1} less to cast for each storied permanent you control. (Enchantments and legendary permanents are storied.)
Counter target spell.
Draw a card.

Whenever Apex of Augmentation attacks, other creatures you control can't be blocked this turn.

At the beginning of your upkeep, if an opponent controls more creatures than you, you may reveal the top seven cards of your library. Target opponent chooses a creature card revealed this way. Put that card onto the battlefield, and the rest into your graveyard.

At the beginning of your upkeep, if you control ten or more storied permanents, you win the game. (Enchantments and legendary permanents are storied.)

Other creatures you control can't attack or block alone.

Flash
Flying
As long as an opponent controls more creatures than you, Arbiter of the Scales gets +2/+2 and has first strike and lifelink.

Whenever Arisen Rider attacks, creatures your opponents control get -1/-1 until end of turn.
If Arisen Rider or another creature or planeswalker would die, exile it instead.

When Arisen Troops dies, you may destroy target creature that was dealt damage this turn.

Trample
Arpechian Champion can only attack or block alone.
Whenever a land you control enters, put a +1/+1 counter on Arpechian Champion.

{T}: Add {C}.
{T}: Add one mana of any color. Activate only if you control a transformed permanent.

Creatures with power greater than Aspiring Recluse's can't block it.
Whenever Aspiring Recluse deals combat damage to a player, you may pay {2}. If you do, transform it.

When Atlas of Worlds enters, search your library for any number of land cards with different names and exile them, then shuffle.
You may play lands exiled with Atlas of Worlds.

You may put a creature card from your hand onto the battlefield. That creature gains haste until end of turn. Sacrifice that creature at the beginning of the next end step unless you pay its mana cost reduced by up to {3}{R}{R}.

Flash
When Augmented Spawn enters, create a 1/1 blue Merfolk creature token for each Island you control.
{U}, Sacrifice a Merfolk: Augmented Spawn gains hexproof until end of turn.

Choose target creature or planeswalker. Its controller may exile it. If that player doesn't, they sacrifice all other creatures and planeswalkers they control.

{R}, {T}: Put a luster counter on Awestone.
{1}{R}, {T}: Add {R} for each luster counter on Awestone.
{2}{R}, {T}: Until end of turn, gain control of target nonland permanent with mana value less than or equal to the number of luster counters on Awestone and it gains haste. Untap that permanent. Activate only during your turn.

{X}{X}, {T}: Draw X cards, then choose X cards in your hand and discard the rest.

You may play cards exiled with Azamir planeswalkers.
[+2]: Search each player's library for a card and exile it. Shuffle each library searched this way.
[–3]: Each opponent chooses a permanent they control for each permanent type, then exiles those permanents.
[–8]: Exile all cards your opponents own from outside the game. Until end of turn, you may cast spells without paying their mana costs and you may play cards exiled with Azamir planeswalkers.

Whenever Babbling Experiment or another creature you control enters, target player mills two cards.

Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)

Mark (Whenever this creature attacks, mark target creature until end of turn.)
Whenever Backalley Silencer deals combat damage to a player, destroy target marked creature.

Non-Actor creatures can't block this turn.