Kroxa, Titan of Death's Hunger

When Kroxa enters, sacrifice it unless it escaped.
Whenever Kroxa enters or attacks, each opponent discards a card, then each opponent who didn't discard a nonland card this way loses 3 life.
Escape—{B}{B}{R}{R}, Exile five other cards from your graveyard. (You may cast this card from your graveyard for its escape cost.)

Primal Beyond

As Primal Beyond enters, you may reveal an Elemental card from your hand. If you don't, Primal Beyond enters tapped.
{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast an Elemental spell or activate an ability of an Elemental.

Lightning Skelemental

Trample, haste
Whenever Lightning Skelemental deals combat damage to a player, that player discards two cards.
At the beginning of the end step, sacrifice Lightning Skelemental.

Ball Lightning

Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)
Haste (This creature can attack and {T} as soon as it comes under your control.)
At the beginning of the end step, sacrifice Ball Lightning.

Swamp

Den of the Bugbear

If you control two or more other lands, Den of the Bugbear enters tapped.
{T}: Add {R}.
{3}{R}: Until end of turn, Den of the Bugbear becomes a 3/2 red Goblin creature with "Whenever this creature attacks, create a 1/1 red Goblin creature token that's tapped and attacking." It's still a land.

Collateral Damage

As an additional cost to cast this spell, sacrifice a creature.
Collateral Damage deals 3 damage to any target.

Terminate

Destroy target creature. It can't be regenerated.

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Inquisition of Kozilek

Target player reveals their hand. You choose a nonland card from it with mana value 3 or less. That player discards that card.

Blackcleave Cliffs

Blackcleave Cliffs enters tapped unless you control two or fewer other lands.
{T}: Add {B} or {R}.

Village Rites

As an additional cost to cast this spell, sacrifice a creature.
Draw two cards.

Mountain

Sulfurous Springs

{T}: Add {C}.
{T}: Add {B} or {R}. Sulfurous Springs deals 1 damage to you.

Unearth

Return target creature card with mana value 3 or less from your graveyard to the battlefield.
Cycling {2} ({2}, Discard this card: Draw a card.)

Graven Cairns

{T}: Add {C}.
{B/R}, {T}: Add {B}{B}, {B}{R}, or {R}{R}.

Slaughter Games

This spell can't be countered.
Choose a nonland card name. Search target opponent's graveyard, hand, and library for any number of cards with that name and exile them. Then that player shuffles.

Flamekin Harbinger

When Flamekin Harbinger enters, you may search your library for an Elemental card, reveal it, then shuffle and put that card on top.

Dreadbore

Thunderkin Awakener

Haste
Whenever Thunderkin Awakener attacks, choose target Elemental creature card in your graveyard with toughness less than Thunderkin Awakener's toughness. Return that card to the battlefield tapped and attacking. Sacrifice it at the beginning of the next end step.

Dragonskull Summit

Dragonskull Summit enters tapped unless you control a Swamp or a Mountain.
{T}: Add {B} or {R}.