Chain Reaction

Chain Reaction deals X damage to each creature, where X is the number of creatures on the battlefield.

Fumigate

Destroy all creatures. You gain 1 life for each creature destroyed this way.

Hour of Reckoning

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
Destroy all nontoken creatures.

Hazardous Blast

Hazardous Blast deals 1 damage to each creature your opponents control. Creatures your opponents control can't block this turn.

Phyrexian Rebirth

Destroy all creatures, then create an X/X colorless Phyrexian Horror artifact creature token, where X is the number of creatures destroyed this way.

Elspeth Tirel

+2: You gain 1 life for each creature you control.
−2: Create three 1/1 white Soldier creature tokens.
−5: Destroy all other permanents except for lands and tokens.

The Eternal Wanderer

No more than one creature can attack The Eternal Wanderer each combat.
+1: Exile up to one target artifact or creature. Return that card to the battlefield under its owner's control at the beginning of that player's next end step.
0: Create a 2/2 white Samurai creature token with double strike.
−4: For each player, choose a creature that player controls. Each player sacrifices all creatures they control not chosen this way.

Cinderslash Ravager

This spell costs {1} less to cast for each permanent you control with oil counters on it.
Vigilance
When Cinderslash Ravager enters, it deals 1 damage to each creature your opponents control.

Culling Ritual

Destroy each nonland permanent with mana value 2 or less. Add {B} or {G} for each permanent destroyed this way.

Merciless Eviction

Choose one —
• Exile all artifacts.
• Exile all creatures.
• Exile all enchantments.
• Exile all planeswalkers.

The Filigree Sylex

{T}: Put an oil counter on The Filigree Sylex.
{T}, Sacrifice The Filigree Sylex: Destroy each nonland permanent with mana value equal to the number of oil counters on The Filigree Sylex.
{T}, Remove ten oil counters from among permanents you control and sacrifice The Filigree Sylex: It deals 10 damage to any target.

White Sun's Twilight

You gain X life. Create X 1/1 colorless Phyrexian Mite artifact creature tokens with toxic 1 and "This creature can't block." If X is 5 or more, destroy all other creatures. (Players dealt combat damage by a creature with toxic 1 also get a poison counter.)