Plains

Lightning Helix

Lightning Helix deals 3 damage to any target and you gain 3 life.

Glory-Bound Initiate

You may exert Glory-Bound Initiate as it attacks. When you do, it gets +1/+3 and gains lifelink until end of turn. (An exerted creature won't untap during your next untap step.)

Declaration in Stone

Exile target creature and all other creatures its controller controls with the same name as that creature. That player investigates for each nontoken creature exiled this way.

To Arms!

Untap all creatures you control.
Draw a card.

Augusta, Dean of Order

Other tapped creatures you control get +1/+0.
Other untapped creatures you control get +0/+1.
Whenever you attack, untap each creature you control, then tap any number of creatures you control.

Plargg, Dean of Chaos

{T}, Discard a card: Draw a card.
{4}{R}, {T}: Reveal cards from the top of your library until you reveal a nonlegendary, nonland card with mana value 3 or less. You may cast that card without paying its mana cost. Put all revealed cards not cast this way on the bottom of your library in a random order.

Plargg, Dean of Chaos // Augusta, Dean of Order

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Khenra Scrapper

Menace
You may exert Khenra Scrapper as it attacks. When you do, it gets +2/+0 until end of turn. (An exerted creature won't untap during your next untap step.)

Dauntless Aven

Flying
Whenever Dauntless Aven attacks, untap target creature you control.

Victory

Aftermath (Cast this spell only from your graveyard. Then exile it.)
Target creature gains double strike until end of turn.

Onward

Target creature gets +X/+0 until end of turn, where X is its power.

Onward // Victory

Vizier of the True

You may exert Vizier of the True as it attacks. (It won't untap during your next untap step.)
Whenever you exert a creature, tap target creature an opponent controls.

Oketra's Avenger

You may exert Oketra's Avenger as it attacks. When you do, prevent all combat damage that would be dealt to it this turn. (An exerted creature won't untap during your next untap step.)

Mountain

Nef-Crop Entangler

Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)
You may exert Nef-Crop Entangler as it attacks. When you do, it gets +1/+2 until end of turn. (An exerted creature won't untap during your next untap step.)

Resolute Survivors

You may exert Resolute Survivors as it attacks. (It won't untap during your next untap step.)
Whenever you exert a creature, Resolute Survivors deals 1 damage to each opponent and you gain 1 life.