Tajuru Warcaller

Rally — Whenever Tajuru Warcaller or another Ally enters the battlefield under your control, creatures you control get +2/+2 until end of turn.

Urza's Rebuff

Choose one —
• Counter target spell.
• Tap up to two target creatures.

Ertai's Scorn

This spell costs {U} less to cast if an opponent cast two or more spells this turn.
Counter target spell.

Overwhelming Encounter

Creatures you control gain vigilance and trample until end of turn. Roll a d20.
1—9 | Creatures you control get +2/+2 until end of turn.
10—19 | Put two +1/+1 counters on each creature you control.
20 | Put four +1/+1 counters on each creature you control.

Tromp the Domains

Domain — Until end of turn, creatures you control gain trample and get +1/+1 for each basic land type among lands you control.

Ruxa, Patient Professor

Whenever Ruxa, Patient Professor enters the battlefield or attacks, return target creature card with no abilities from your graveyard to your hand.
Creatures you control with no abilities get +1/+1.
For each creature you control with no abilities, you may have that creature assign its combat damage as though it weren't blocked.

Overwhelm

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
Creatures you control get +3/+3 until end of turn.

Mirrorshell Crab

Ward {3} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {3}.)
Channel — {2}{U}, Discard Mirrorshell Crab: Counter target spell or ability unless its controller pays {3}.

Forest

Zellix, Sanity Flayer

Hive Mind — Whenever a player mills one or more creature cards, you create a 1/1 black Horror creature token.
{1}, {T}: Target player mills three cards.
Choose a Background (You can have a Background as a second commander.)

Halsin, Emerald Archdruid

{1}: Until end of turn, target token you control becomes a green Bear creature with base power and toughness 4/4 in addition to its other colors and types.
Choose a Background (You can have a Background as a second commander.)

Cloakwood Hermit

Commander creatures you own have "At the beginning of your end step, if a creature card was put into your graveyard from anywhere this turn, create two tapped 1/1 green Squirrel creature tokens."

Command Tower

{T}: Add one mana of any color in your commander's color identity.

Tetsuko Umezawa, Fugitive

Creatures you control with power or toughness 1 or less can't be blocked.

Cloakwood Swarmkeeper

Gathered Swarm — Whenever one or more tokens enter the battlefield under your control, put a +1/+1 counter on Cloakwood Swarmkeeper.

Tajuru Beastmaster

Rally — Whenever Tajuru Beastmaster or another Ally enters the battlefield under your control, creatures you control get +1/+1 until end of turn.

Undercity Upheaval

Undergrowth — Distribute X +1/+1 counters among any number of target creatures you control, where X is the number of creature cards in your graveyard as you cast this spell. Creatures you control gain vigilance until end of turn.

Take to the Streets

Creatures you control get +2/+2 until end of turn. Citizens you control get an additional +1/+1 and gain vigilance until end of turn.

Millikin

{T}, Mill a card: Add {C}. (To mill a card, put the top card of your library into your graveyard.)

You Meet in a Tavern

Choose one —
• Form a Party — Look at the top five cards of your library. You may reveal any number of creature cards from among them and put them into your hand. Put the rest on the bottom of your library in a random order.
• Start a Brawl — Creatures you control get +2/+2 until end of turn.

Overcome

Creatures you control get +2/+2 and gain trample until end of turn.

Deranged Assistant

Merfolk Windrobber

Flying
Whenever Merfolk Windrobber deals combat damage to a player, that player mills a card. (They put the top card of their library into their graveyard.)
Sacrifice Merfolk Windrobber: Draw a card. Activate only if an opponent has eight or more cards in their graveyard.

Disruption Protocol

As an additional cost to cast this spell, tap an untapped artifact you control or pay {1}.
Counter target spell.

Contested War Zone

Whenever a creature deals combat damage to you, that creature's controller gains control of Contested War Zone.
{T}: Add {C}.
{1}, {T}: Attacking creatures get +1/+0 until end of turn.

Noxious Assault

Creatures you control get +2/+2 until end of turn. Whenever a creature blocks this turn, its controller gets a poison counter.

Island

Klothys's Design

Creatures you control get +X/+X until end of turn, where X is your devotion to green. (Each {G} in the mana costs of permanents you control counts toward your devotion to green.)