Fling

As an additional cost to cast this spell, sacrifice a creature.
Fling deals damage equal to the sacrificed creature's power to any target.

Plains

Clever Lumimancer

Magecraft — Whenever you cast or copy an instant or sorcery spell, Clever Lumimancer gets +2/+2 until end of turn.

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Maximize Velocity

Target creature gets +1/+1 and gains haste until end of turn.
Jump-start (You may cast this card from your graveyard by discarding a card in addition to paying its other costs. Then exile this card.)

Kiln Fiend

Whenever you cast an instant or sorcery spell, Kiln Fiend gets +3/+0 until end of turn.

Arid Mesa

{T}, Pay 1 life, Sacrifice Arid Mesa: Search your library for a Mountain or Plains card, put it onto the battlefield, then shuffle.

Mountain

Dreadhorde Arcanist

Trample
Whenever Dreadhorde Arcanist attacks, you may cast target instant or sorcery card with mana value less than or equal to Dreadhorde Arcanist's power from your graveyard without paying its mana cost. If that spell would be put into your graveyard, exile it instead.

Temur Battle Rage

Target creature gains double strike until end of turn.
Ferocious — That creature also gains trample until end of turn if you control a creature with power 4 or greater.

Barge In

Target attacking creature gets +2/+2 until end of turn. Each attacking non-Human creature gains trample until end of turn.

Furious Resistance

Target blocking creature gets +3/+0 and gains first strike until end of turn.

Mutagenic Growth

({G/P} can be paid with either {G} or 2 life.)
Target creature gets +2/+2 until end of turn.

Sacred Foundry

({T}: Add {R} or {W}.)
As Sacred Foundry enters, you may pay 2 life. If you don't, it enters tapped.

Assault Strobe

Target creature gains double strike until end of turn. (It deals both first-strike and regular combat damage.)

Lava Dart

Lava Dart deals 1 damage to any target.
Flashback—Sacrifice a Mountain. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Inspiring Vantage

Inspiring Vantage enters tapped unless you control two or fewer other lands.
{T}: Add {R} or {W}.