Voracious Greatshark

Flash (You may cast this spell any time you could cast an instant.)
When this creature enters, counter target artifact or creature spell.

Spiny Starfish

{U}: Regenerate Spiny Starfish.
At the beginning of each end step, if Spiny Starfish regenerated this turn, create a 0/1 blue Starfish creature token for each time it regenerated this turn.

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.

Brushwagg

Whenever Brushwagg blocks or becomes blocked, it gets -2/+2 until end of turn.

Blurred Mongoose

This spell can't be countered.
Shroud (This creature can't be the target of spells or abilities.)

Wolverine Pack

Rampage 2 (Whenever this creature becomes blocked, it gets +2/+2 until end of turn for each creature blocking it beyond the first.)

Giant Oyster

You may choose not to untap Giant Oyster during your untap step.
{T}: For as long as Giant Oyster remains tapped, target tapped creature doesn't untap during its controller's untap step, and at the beginning of each of your draw steps, put a -1/-1 counter on that creature. When Giant Oyster leaves the battlefield or becomes untapped, remove all -1/-1 counters from the creature.

Pygmy Hippo

Whenever Pygmy Hippo attacks and isn't blocked, you may have defending player activate a mana ability of each land they control and lose all unspent mana. If you do, Pygmy Hippo assigns no combat damage this turn and at the beginning of your next main phase this turn, you add an amount of {C} equal to the amount of mana that player lost this way.

Slith Predator

Trample
Whenever Slith Predator deals combat damage to a player, put a +1/+1 counter on it.

Raised by Giants

Commander creatures you own have base power and toughness 10/10 and are Giants in addition to their other types.

Gibbering Hyenas

Gibbering Hyenas can't block black creatures.

Chambered Nautilus

Whenever Chambered Nautilus becomes blocked, you may draw a card.

Cockatrice

Flying
Whenever Cockatrice blocks or becomes blocked by a non-Wall creature, destroy that creature at end of combat.

Steamcore Scholar

Flying, vigilance
When Steamcore Scholar enters, draw two cards. Then discard two cards unless you discard an instant or sorcery card or a creature card with flying.

Volo, Guide to Monsters

Whenever you cast a creature spell that doesn't share a creature type with a creature you control or a creature card in your graveyard, copy that spell. (A copy of a creature spell becomes a token.)

Waildrifter

Flying
If Waildrifter would be put into a graveyard from anywhere, exile it instead.

Galedrifter

Flying
Disturb {4}{U} (You may cast this card from your graveyard transformed for its disturb cost.)

Galedrifter // Waildrifter

Grove's Bounty

Distribute X +1/+1 counters among any number of target creatures you control. (Then exile this card. You may cast the creature later from exile.)

Elusive Otter

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Creatures with power less than Elusive Otter's power can't block it.

Elusive Otter // Grove's Bounty

Dinosaur Egg

Evolve (Whenever a creature you control enters, if that creature has greater power or toughness than this creature, put a +1/+1 counter on this creature.)
When Dinosaur Egg dies, you may discover X, where X is its toughness.

Spitting Slug

Whenever Spitting Slug blocks or becomes blocked, you may pay {1}{G}. If you do, Spitting Slug gains first strike until end of turn. Otherwise, each creature blocking or blocked by Spitting Slug gains first strike until end of turn.

Thalakos Drifters

Discard a card: Thalakos Drifters gains shadow until end of turn. (It can block or be blocked by only creatures with shadow.)

Coiling Woodworm

Coiling Woodworm's power is equal to the number of Forests on the battlefield.

Gnoll Hunter

Pack tactics — Whenever Gnoll Hunter attacks, if you attacked with creatures with total power 6 or greater this combat, put a +1/+1 counter on Gnoll Hunter.

Brine Hag

When Brine Hag dies, change the base power and toughness of all creatures that dealt damage to it this turn to 0/2. (This effect lasts indefinitely.)

Quarry Hauler

When Quarry Hauler enters, for each kind of counter on target permanent, put another counter of that kind on it or remove one from it.

Homarid Shaman

Bouncing Beebles

Bouncing Beebles can't be blocked as long as defending player controls an artifact.

Ridgescale Tusker

When Ridgescale Tusker enters, put a +1/+1 counter on each other creature you control.

Walking Sponge

{T}: Target creature loses your choice of flying, first strike, or trample until end of turn.

Volo, Itinerant Scholar

When Volo enters, create Volo's Journal, a legendary colorless artifact token with hexproof and "Whenever you cast a creature spell, note one of its creature types that hasn't been noted for this artifact."
{2}, {T}: Draw a card for each creature type noted for target permanent you control named Volo's Journal.
Choose a Background

Excavation Mole

Trample
When Excavation Mole enters, mill three cards.

Metathran Aerostat

Flying
{X}{U}: You may put a creature card with mana value X from your hand onto the battlefield. If you do, return Metathran Aerostat to its owner's hand.

Joven's Ferrets

Whenever Joven's Ferrets attacks, it gets +0/+2 until end of turn.
At end of combat, tap all creatures that blocked Joven's Ferrets this turn. They don't untap during their controller's next untap step.