Breena, the Demagogue

Flying
Whenever a player attacks one of your opponents, if that opponent has more life than another of your opponents, that attacking player draws a card and you put two +1/+1 counters on a creature you control.

Dark Ritual

Ghostly Prison

Creatures can't attack you unless their controller pays {2} for each creature they control that's attacking you.

Scriv, the Obligator

Flying, deathtouch
Whenever Scriv enters or attacks, create a white Aura enchantment token named Contract attached to target creature an opponent controls. The token has enchant creature and "Whenever enchanted creature attacks, it gets +2/+0 until end of turn if it's attacking one of your opponents. Otherwise, its controller loses 2 life."

Killian, Decisive Mentor

Whenever an enchantment you control enters, tap up to one target creature and goad it. (Until your next turn, that creature attacks each combat if able and attacks a player other than you if able.)
Whenever one or more creatures that are enchanted by an Aura you control attack, draw a card.

Songbirds' Blessing

Enchant creature
Whenever enchanted creature attacks, reveal cards from the top of your library until you reveal an Aura card. You may put that card onto the battlefield. If you don't, put it into your hand. Put the rest on the bottom of your library in a random order.

Anguished Unmaking

Exile target nonland permanent. You lose 3 life.

Sol Ring

Eriette of the Charmed Apple

Each creature that's enchanted by an Aura you control can't attack you or planeswalkers you control.
At the beginning of your end step, each opponent loses X life and you gain X life, where X is the number of Auras you control.

Doomwake Giant

Constellation — Whenever this creature or another enchantment you control enters, creatures your opponents control get -1/-1 until end of turn.