Cower in Fear

Creatures your opponents control get -1/-1 until end of turn.

Unnerve

Mire in Misery

Each opponent sacrifices a creature or enchantment.

Wit's End

Fraying Omnipotence

Each player loses half their life, then discards half the cards in their hand, then sacrifices half the creatures they control. Round up each time.

Capital Punishment

Council's dilemma — Starting with you, each player votes for death or taxes. Each opponent sacrifices a creature for each death vote and discards a card for each taxes vote.

Dark Intimations

Each opponent sacrifices a creature or planeswalker, then discards a card. You return a creature or planeswalker card from your graveyard to your hand, then draw a card.
When you cast a Bolas planeswalker spell, exile Dark Intimations from your graveyard. That planeswalker enters the battlefield with an additional loyalty counter on it.

Commence the Endgame

This spell can't be countered.
Draw two cards, then amass Zombies X, where X is the number of cards in your hand. (Put X +1/+1 counters on an Army you control. It's also a Zombie. If you don't control an Army, create a 0/0 black Zombie Army creature token first.)

Patient Rebuilding

At the beginning of your upkeep, target opponent mills three cards, then you draw a card for each land card put into their graveyard this way.