Devilish Valet

Trample, haste
Alliance — Whenever another creature you control enters, double this creature's power until end of turn.

Frenzied Goblin

Whenever this creature attacks, you may pay {R}. If you do, target creature can't block this turn.

Bolt Hound

Haste (This creature can attack and {T} as soon as it comes under your control.)
Whenever this creature attacks, other creatures you control get +1/+0 until end of turn.

Unleash Fury

Double the power of target creature until end of turn.

Borderland Marauder

Whenever this creature attacks, it gets +2/+0 until end of turn.

Hardened Berserker

Whenever this creature attacks, the next spell you cast this turn costs {1} less to cast.

Goblin Piledriver

Protection from blue (This creature can't be blocked, targeted, dealt damage, or enchanted by anything blue.)
Whenever this creature attacks, it gets +2/+0 until end of turn for each other attacking Goblin.

Predator Ooze

Indestructible (Damage and effects that say "destroy" don't destroy this creature.)
Whenever this creature attacks, put a +1/+1 counter on it.
Whenever a creature dealt damage by this creature this turn dies, put a +1/+1 counter on this creature.

Lord of the Ulvenwald

Other Wolves and Werewolves you control get +1/+1.
Whenever this creature attacks, add {R} or {G}. Until end of turn, you don't lose this mana as steps and phases end.
Nightbound (If a player casts at least two spells during their own turn, it becomes day next turn.)

Kessig Naturalist

Whenever this creature attacks, add {R} or {G}. Until end of turn, you don't lose this mana as steps and phases end.
Daybound (If a player casts no spells during their own turn, it becomes night next turn.)

Kessig Naturalist // Lord of the Ulvenwald

Etali, Primal Storm

Whenever Etali attacks, exile the top card of each player's library, then you may cast any number of spells from among those cards without paying their mana costs.

Rulik Mons, Warren Chief

Menace (This creature can't be blocked except by two or more creatures.)
Whenever Rulik Mons attacks, look at the top card of your library. If it's a land card, you may put it onto the battlefield tapped. If you didn't put a card onto the battlefield this way, create a 1/1 red Goblin creature token.

Choose Your Weapon

Choose one —
• Two-Weapon Fighting — Double target creature's power and toughness until end of turn.
• Archery — This spell deals 5 damage to target creature with flying.

Unnatural Growth

At the beginning of each combat, double the power and toughness of each creature you control until end of turn.

Omnivorous Flytrap

Delirium — Whenever this creature enters or attacks, if there are four or more card types among cards in your graveyard, distribute two +1/+1 counters among one or two target creatures. Then if there are six or more card types among cards in your graveyard, double the number of +1/+1 counters on those creatures.

Tectonic Giant

Whenever this creature attacks or becomes the target of a spell an opponent controls, choose one —
• This creature deals 3 damage to each opponent.
• Exile the top two cards of your library. Choose one of them. Until the end of your next turn, you may play that card.

Conduit of Emrakul

Whenever this creature attacks, add {C}{C} at the beginning of your next main phase this turn.

Conduit of Storms

Whenever this creature attacks, add {R} at the beginning of your next main phase this turn.
{3}{R}{R}: Transform this creature.

Conduit of Storms // Conduit of Emrakul

Graven Abomination

Whenever this creature attacks, exile target card from defending player's graveyard.

Wulfgar of Icewind Dale

Melee (Whenever this creature attacks, it gets +1/+1 until end of turn for each opponent you attacked this combat.)
If a creature you control attacking causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Zopandrel, Hunger Dominus

Reach
At the beginning of each combat, double the power and toughness of each creature you control until end of turn.
{G/P}{G/P}, Sacrifice two other creatures: Put an indestructible counter on Zopandrel. ({G/P} can be paid with either {G} or 2 life.)

Durnan of the Yawning Portal

Whenever Durnan attacks, look at the top four cards of your library. You may exile a creature card from among them. Put the rest on the bottom of your library in any order. For as long as that card remains exiled, you may cast it. That spell has undaunted. (It costs {1} less to cast for each opponent.)
Choose a Background (You can have a Background as a second commander.)

Civic Gardener

Whenever this creature attacks, untap target creature or land.

Radha, Heir to Keld

Whenever Radha attacks, you may add {R}{R}.
{T}: Add {G}.

Targ Nar, Demon-Fang Gnoll

Pack tactics — Whenever Targ Nar attacks, if you attacked with creatures with total power 6 or greater this combat, attacking creatures get +1/+0 until end of turn.
{2}{R}{G}: Double Targ Nar's power and toughness until end of turn.

Deathgorge Scavenger

Whenever this creature enters or attacks, you may exile target card from a graveyard. If a creature card is exiled this way, you gain 2 life. If a noncreature card is exiled this way, this creature gets +1/+1 until end of turn.

Coastline Marauders

Trample
Whenever this creature attacks, it gets +1/+0 until end of turn for each land defending player controls.
Encore {4}{R}{R} ({4}{R}{R}, Exile this card from your graveyard: For each opponent, create a token copy that attacks that opponent this turn if able. They gain haste. Sacrifice them at the beginning of the next end step. Activate only as a sorcery.)

Tuya Bearclaw

Whenever Tuya Bearclaw attacks, it gets +X/+X until end of turn, where X is the greatest power among other creatures you control.

Flesh Burrower

Deathtouch
Whenever this creature attacks, another target creature you control gains deathtouch until end of turn.

Malamet Brawler

Whenever this creature attacks, target attacking creature gains trample until end of turn.

Flamerush Rider

Whenever this creature attacks, create a token that's a copy of another target attacking creature and that's tapped and attacking. Exile the token at end of combat.
Dash {2}{R}{R} (You may cast this spell for its dash cost. If you do, it gains haste, and it's returned from the battlefield to its owner's hand at the beginning of the next end step.)