msem-instigator

Trample
Whenever a creature you don't control dies, you gain 2 life.
Whenever you gain life, put that many +1/+1 counters on target creature you control.

Trample
When The Shepherd of Nowhere enters the battlefield, each player sacrifices each other nontoken creature they control.
Whenever another nontoken creature you control dies, create a token that's a copy of that creature.

Discard a card: Unseen Maniac gets +1/+1 and can't be blocked this turn.
Whenever Unseen Maniac deals combat damage to a player, draw a card.

Unstoppable Slaughter deals 1 damage to each creature and each player. Whenever a creature dealt damage by Unstoppable Slaughter this turn dies this turn, repeat that process.

As long as you control exactly one creature, no more than one creature can attack or block each combat.

Flying
Whenever you cast a spell from exile, each opponent loses 2 life.

Destroy target creature or planeswalker. Each player loses life equal to that permanent's mana value.

Destroy target nonland permanent. You may return a card that shares a card type with that permanent from your graveyard to your hand.

At the beginning of your upkeep, each player discards a card.
Whenever Waking Watcher attacks, if defending player has no cards in hand, it gets +3/+3 and gains menace until end of turn.

Whenever an opponent casts a spell, that player mills X cards, where X is that spell's mana value.

Flash
When Wiretapper enters the battlefield, choose one —
• Exile target spell. For as long as that card remains exiled, its owner may play it. A spell cast this way costs {2} more to cast.
• Create a copy of the card with target spell's name. You may cast the copy. (You still pay its costs.)

Zealous Rabble gets +1/+1 for each creature token you control.
At the beginning of your end step, if you're horrific, create a token that's a copy of Zealous Rabble, except it doesn't have this ability. (You're horrific as long as you've sacrificed a permanent or discarded a card this turn.)