Keen-Eyed Curator

As long as there are four or more card types among cards exiled with this creature, it gets +4/+4 and has trample.
{1}: Exile target card from a graveyard.

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.)

Wandertale Mentor

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

Roughshod Duo

Trample
Whenever you expend 4, target creature you control gets +1/+1 and gains trample until end of turn. (You expend 4 as you spend your fourth total mana to cast spells during a turn.)

Coati Scavenger

Descend 4 — When this creature enters, if there are four or more permanent cards in your graveyard, return target permanent card from your graveyard to your hand.

Bakersbane Duo

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

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.

Scrappy Bruiser

Whenever this creature attacks, up to one target attacking creature gets +2/+0 and gains trample until end of turn. Return that creature to its owner's hand at end of combat. (Return it only if it's on the battlefield.)

Teapot Slinger

Menace
Whenever you expend 4, this creature deals 2 damage to each opponent. (You expend 4 as you spend your fourth total mana to cast spells during a turn.)

Trailtracker Scout

{T}: Add one mana of any color.
Whenever you expend 8, return up to one target permanent card from your graveyard to your hand. (You expend 8 as you spend your eighth total mana to cast spells during a turn.)

Brazen Collector

First strike
Whenever this creature attacks, add {R}. Until end of turn, you don't lose this mana as steps and phases end.

Junkblade Bruiser

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

Raccoon Rallier

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

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 this creature enters, if the gift was promised, destroy target artifact or enchantment an opponent controls.

Fetch Quest

Mill seven cards. Then put a creature, enchantment, or land card from among the milled cards onto the battlefield.

Bramble Familiar

{T}: Add {G}.
{1}{G}, {T}, Discard a card: Return this creature to its owner's hand.

Bramble Familiar // Fetch Quest

Bello, Bard of the Brambles

During your turn, each non-Equipment artifact and non-Aura enchantment you control with mana value 4 or greater is a 4/4 Elemental creature in addition to its other types and has indestructible, haste, and "Whenever this creature deals combat damage to a player, draw a card."

Bark-Knuckle Boxer

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