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.

Archon of Cruelty

Flying
Whenever Archon of Cruelty enters or attacks, target opponent sacrifices a creature or planeswalker of their choice, discards a card, and loses 3 life. You draw a card and gain 3 life.

Winota, Joiner of Forces

Whenever a non-Human creature you control attacks, look at the top six cards of your library. You may put a Human creature card from among them onto the battlefield tapped and attacking. It gains indestructible until end of turn. Put the rest of the cards on the bottom of your library in a random order.

Graveyard Glutton

Ward—Discard a card.
Whenever Graveyard Glutton enters or attacks, exile up to two target cards from graveyards. For each creature card exiled this way, each opponent loses 1 life and you gain 1 life.
Nightbound (If a player casts at least two spells during their own turn, it becomes day next turn.)

Graveyard Trespasser

Ward—Discard a card.
Whenever Graveyard Trespasser enters or attacks, exile up to one target card from a graveyard. If a creature card was exiled this way, each opponent loses 1 life and you gain 1 life.
Daybound (If a player casts no spells during their own turn, it becomes night next turn.)

Graveyard Trespasser // Graveyard Glutton

Mardu Roughrider

Whenever Mardu Roughrider attacks, target creature can't block this turn.

Isshin, Two Heavens as One

If a creature attacking causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Grotag Thrasher

Whenever Grotag Thrasher attacks, target creature can't block this turn.

Lightfoot Rogue

Sneak Attack — Whenever Lightfoot Rogue attacks, roll a d20.
1—9 | Lightfoot Rogue gains deathtouch until end of turn.
10—19 | It gets +1/+0 and gains deathtouch until end of turn.
20 | It gets +3/+0 and gains first strike and deathtouch until end of turn.

Mardu Ascendancy

Whenever a nontoken creature you control attacks, create a 1/1 red Goblin creature token that's tapped and attacking.
Sacrifice Mardu Ascendancy: Creatures you control get +0/+3 until end of turn.

Galepowder Mage

Flying
Whenever Galepowder Mage attacks, exile another target creature. Return that card to the battlefield under its owner's control at the beginning of the next end step.

Underworld Sentinel

Whenever Underworld Sentinel attacks, exile target creature card from your graveyard.
When Underworld Sentinel dies, put all cards exiled with it onto the battlefield.

Rogue's Passage

{T}: Add {C}.
{4}, {T}: Target creature can't be blocked this turn.

Campaign of Vengeance

Whenever a creature you control attacks, defending player loses 1 life and you gain 1 life.

Linden, the Steadfast Queen

Vigilance (Attacking doesn't cause this creature to tap.)
Whenever a white creature you control attacks, you gain 1 life.

Laelia, the Blade Reforged

Haste
Whenever Laelia, the Blade Reforged attacks, exile the top card of your library. You may play that card this turn.
Whenever one or more cards are put into exile from your library and/or your graveyard, put a +1/+1 counter on Laelia.

Clamor Shaman

Riot (This creature enters with your choice of a +1/+1 counter or haste.)
Whenever Clamor Shaman attacks, target creature an opponent controls can't block this turn.

Militia's Pride

Whenever a nontoken creature you control attacks, you may pay {W}. If you do, create a 1/1 white Kithkin Soldier creature token that's tapped and attacking.

Orim's Prayer

Whenever one or more creatures attack you, you gain 1 life for each attacking creature.

Tempered in Solitude

Whenever a creature you control attacks alone, exile the top card of your library. You may play that card this turn.

Goblin Traprunner

Whenever Goblin Traprunner attacks, flip three coins. For each flip you win, create a 1/1 red Goblin creature token that's tapped and attacking.

Impulsive Maneuvers

Whenever a creature attacks, flip a coin. If you win the flip, the next time that creature would deal combat damage this turn, it deals double that damage instead. If you lose the flip, the next time that creature would deal combat damage this turn, prevent that damage.

Goblin Heelcutter

Whenever Goblin Heelcutter attacks, target creature can't block this turn.
Dash {2}{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.)

Chaos Channeler

Wild Magic Surge — Whenever Chaos Channeler attacks, roll a d20.
1—9 | Exile the top card of your library. You may play it this turn.
10—19 | Exile the top two cards of your library. You may play them this turn.
20 | Exile the top three cards of your library. You may play them this turn.

Olivia, Crimson Bride

Flying, haste
Whenever Olivia, Crimson Bride attacks, return target creature card from your graveyard to the battlefield tapped and attacking. It gains "When you don't control a legendary Vampire, exile this creature."

Hoarding Ogre

Whenever Hoarding Ogre attacks, roll a d20.
1—9 | Create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")
10—19 | Create two Treasure tokens.
20 | Create three Treasure tokens.

Gleam of Battle

Whenever a creature you control attacks, put a +1/+1 counter on it.

Brutal Hordechief

Whenever a creature you control attacks, defending player loses 1 life and you gain 1 life.
{3}{R/W}{R/W}: Creatures your opponents control block this turn if able, and you choose how those creatures block.

Bruse Tarl, Boorish Herder

Whenever Bruse Tarl, Boorish Herder enters or attacks, target creature you control gains double strike and lifelink until end of turn.
Partner (You can have two commanders if both have partner.)

Hellrider

Haste
Whenever a creature you control attacks, Hellrider deals 1 damage to the player or planeswalker it's attacking.