Coati Scavenger

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

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.

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.)

Brazen Collector

First strike
Whenever Brazen Collector 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, 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.)

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."

Scrappy Bruiser

Whenever Scrappy Bruiser 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.)

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}.