The Skullspore Nexus

This spell costs {X} less to cast, where X is the greatest power among creatures you control.
Whenever one or more nontoken creatures you control die, create a green Fungus Dinosaur creature token with base power and toughness each equal to the total power of those creatures.
{2}, {T}: Double target creature's power until end of turn.

Eldritch Evolution

As an additional cost to cast this spell, sacrifice a creature.
Search your library for a creature card with mana value X or less, where X is 2 plus the sacrificed creature's mana value. Put that card onto the battlefield, then shuffle. Exile Eldritch Evolution.

Harness by Force

Strive — This spell costs {2}{R} more to cast for each target beyond the first.
Gain control of any number of target creatures until end of turn. Untap those creatures. They gain haste until end of turn.

Blazemire Verge

{T}: Add {B}.
{T}: Add {R}. Activate only if you control a Swamp or a Mountain.

Reanimate

Put target creature card from a graveyard onto the battlefield under your control. You lose life equal to its mana value.

Ghalta, Primal Hunger

This spell costs {X} less to cast, where X is the total power of creatures you control.
Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)

Vengeful Possession

Gain control of target creature until end of turn. Untap it. It gains haste until end of turn. You may discard a card. If you do, draw a card.

Korvold, Fae-Cursed King

Flying
Whenever Korvold enters or attacks, sacrifice another permanent.
Whenever you sacrifice a permanent, put a +1/+1 counter on Korvold and draw a card.

Ignoble Hierarch

Exalted (Whenever a creature you control attacks alone, that creature gets +1/+1 until end of turn.)
{T}: Add {B}, {R}, or {G}.

Wrangle

Gain control of target creature with power 4 or less until end of turn. Untap that creature. It gains haste until end of turn.

Diabolic Intent

As an additional cost to cast this spell, sacrifice a creature.
Search your library for a card, put that card into your hand, then shuffle.

Wastewood Verge

{T}: Add {G}.
{T}: Add {B}. Activate only if you control a Swamp or a Forest.

Ziatora, the Incinerator

Flying
At the beginning of your end step, you may sacrifice another creature. When you do, Ziatora deals damage equal to that creature's power to any target and you create three Treasure tokens.

Thornspire Verge

{T}: Add {R}.
{T}: Add {G}. Activate only if you control a Mountain or a Forest.

Feldon of the Third Path

{2}{R}, {T}: Create a token that's a copy of target creature card in your graveyard, except it's an artifact in addition to its other types. It gains haste. Sacrifice it at the beginning of the next end step.