Breaking Point

Any player may have Breaking Point deal 6 damage to them. If no one does, destroy all creatures. Creatures destroyed this way can't be regenerated.

Book Burning

Any player may have Book Burning deal 6 damage to them. If no one does, target player mills six cards.

Rite of Flame

Add {R}{R}, then add {R} for each card named Rite of Flame in each graveyard.

Chain Lightning

Chain Lightning deals 3 damage to any target. Then that player or that permanent's controller may pay {R}{R}. If the player does, they may copy this spell and may choose a new target for that copy.

Etali, Primal Storm

Whenever Etali attacks, exile the top card of each player's library, then you may cast any number of spells from among those cards without paying their mana costs.

Burn from Within

Burn from Within deals X damage to any target. If a creature is dealt damage this way, it loses indestructible until end of turn. If that creature would die this turn, exile it instead.

Geosurge

Add {R}{R}{R}{R}{R}{R}{R}. Spend this mana only to cast artifact or creature spells.

Barktooth Warbeard

Mana Geyser

Add {R} for each tapped land your opponents control.

Bone Dancer

Whenever Bone Dancer attacks and isn't blocked, you may put the top creature card of defending player's graveyard onto the battlefield under your control. If you do, Bone Dancer assigns no combat damage this turn.

Chaos Warp

The owner of target permanent shuffles it into their library, then reveals the top card of their library. If it's a permanent card, they put it onto the battlefield.

Slith Firewalker

Haste
Whenever Slith Firewalker deals combat damage to a player, put a +1/+1 counter on it.

Gila Courser

Whenever Gila Courser attacks while saddled, exile the top card of your library. Until the end of your next turn, you may play that card.
Saddle 1 (Tap any number of other creatures you control with total power 1 or more: This Mount becomes saddled until end of turn. Saddle only as a sorcery.)