Brambleguard Veteran

Whenever you expend 4, Raccoons you control get +1/+1 and gain vigilance until end of turn. (You expend 4 as you spend your fourth total mana to cast spells during a turn.)

Forest

Raccoon Rallier

{T}: Target creature you control gains haste until end of turn. Activate only as a sorcery.

Wandertale Mentor

Whenever you expend 4, put a +1/+1 counter on Wandertale Mentor. (You expend 4 as you spend your fourth total mana to cast spells during a turn.)
{T}: Add {R} or {G}.

Fire-Lit Thicket

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

Rust-Shield Rampager

Offspring {2} (You may pay an additional {2} as you cast this spell. If you do, when this creature enters, create a 1/1 token copy of it.)
This creature can't be blocked by creatures with power 2 or less.

Rockfall Vale

Rockfall Vale enters tapped unless you control two or more other lands.
{T}: Add {R} or {G}.

Bark-Knuckle Boxer

Whenever you expend 4, Bark-Knuckle Boxer gains indestructible until end of turn. (You expend 4 as you spend your fourth total mana to cast spells during a turn.)

Muerra, Trash Tactician

At the beginning of your first main phase, add {R} or {G} for each Raccoon you control.
Whenever you expend 4, you gain 3 life. (You expend 4 as you spend your fourth total mana to cast spells during a turn.)
Whenever you expend 8, exile the top two cards of your library. Until the end of your next turn, you may play those cards.

Bakersbane Duo

When Bakersbane Duo enters, create a Food token.
Whenever you expend 4, Bakersbane Duo gets +1/+1 until end of turn. (You expend 4 as you spend your fourth total mana to cast spells during a turn.)

Scrapshooter

Gift a card (You may promise an opponent a gift as you cast this spell. If you do, when it enters, they draw a card.)
Reach
When Scrapshooter enters, if the gift was promised, destroy target artifact or enchantment an opponent controls.

Copperline Gorge

Copperline Gorge enters tapped unless you control two or fewer other lands.
{T}: Add {R} or {G}.

Junkblade Bruiser

Trample
Whenever you expend 4, Junkblade Bruiser gets +2/+1 until end of turn. (You expend 4 as you spend your fourth total mana to cast spells during a turn.)

Byway Barterer

Menace
Whenever you expend 4, you may discard your hand. If you do, draw two cards. (You expend 4 as you spend your fourth total mana to cast spells during a turn.)