Keep Watch

Mist-Syndicate Naga

Ninjutsu {2}{U} ({2}{U}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
Whenever this creature deals combat damage to a player, create a token that's a copy of this creature.

Epistolary Librarian

Veil of Time — Whenever this creature attacks, you may cast a spell with mana value X or less from your hand without paying its mana cost, where X is the number of attacking creatures.

Devoted Crop-Mate

You may exert this creature as it attacks. When you do, return target creature card with mana value 2 or less from your graveyard to the battlefield. (An exerted creature won't untap during your next untap step.)

Dauntless Avenger

Whenever this creature attacks, return target creature card with mana value 2 or less from your graveyard to the battlefield tapped and attacking.

Bereaved Survivor

When another creature you control dies, transform this creature.

Bereaved Survivor // Dauntless Avenger

Thousand-Faced Shadow

Ninjutsu {2}{U}{U} ({2}{U}{U}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
Flying
When this creature enters from your hand, if it's attacking, create a token that's a copy of another target attacking creature. The token enters tapped and attacking.

Arm with Aether

Until end of turn, creatures you control gain "Whenever this creature deals damage to an opponent, you may return target creature that player controls to its owner's hand."

Bishop of Rebirth

Vigilance
Whenever this creature attacks, you may return target creature card with mana value 3 or less from your graveyard to the battlefield.

Unimpeded Trespasser

Uninvited Geist

Skulk (This creature can't be blocked by creatures with greater power.)
When this creature deals combat damage to a player, transform it.

Uninvited Geist // Unimpeded Trespasser

Looter il-Kor

Shadow (This creature can block or be blocked by only creatures with shadow.)
Whenever this creature deals damage to an opponent, draw a card, then discard a card.

Eternal of Harsh Truths

Afflict 2 (Whenever this creature becomes blocked, defending player loses 2 life.)
Whenever this creature attacks and isn't blocked, draw a card.

Dromoka Captain

First strike
Whenever this creature attacks, bolster 1. (Choose a creature with the least toughness among creatures you control and put a +1/+1 counter on it.)

Ballroom Brawlers

Whenever this creature attacks, this creature and up to one other target creature you control both gain your choice of first strike or lifelink until end of turn.

Identity Thief

Whenever this creature attacks, you may exile another target nontoken creature. If you do, this creature becomes a copy of that creature until end of turn. Return the exiled card to the battlefield under its owner's control at the beginning of the next end step.

Martial Impetus

Enchant creature
Enchanted creature gets +1/+1 and is goaded. (It attacks each combat if able and attacks a player other than you if able.)
Whenever enchanted creature attacks, each other creature that's attacking one of your opponents gets +1/+1 until end of turn.

Medomai the Ageless

Flying
Whenever Medomai deals combat damage to a player, take an extra turn after this one.
Medomai can't attack during extra turns.

Resplendent Griffin

Flying
Ascend (If you control ten or more permanents, you get the city's blessing for the rest of the game.)
Whenever this creature attacks, if you have the city's blessing, put a +1/+1 counter on it.

Dorothea's Retribution

Enchant creature
Enchanted creature has "Whenever this creature attacks, create a 4/4 white Spirit creature token with flying that's tapped and attacking. Sacrifice that token at end of combat."
If Dorothea's Retribution would be put into a graveyard from anywhere, exile it instead.

Dorothea, Vengeful Victim

Flying
When Dorothea attacks or blocks, sacrifice it at end of combat.
Disturb {1}{W}{U} (You may cast this card from your graveyard transformed for its disturb cost.)

Dorothea, Vengeful Victim // Dorothea's Retribution

Invocation of Saint Traft

Enchant creature
Enchanted creature has "Whenever this creature attacks, create a 4/4 white Angel creature token with flying that's tapped and attacking. Exile that token at end of combat."

Slith Strider

Whenever this creature becomes blocked, draw a card.
Whenever this creature deals combat damage to a player, put a +1/+1 counter on it.

Staggering Insight

Enchant creature
Enchanted creature gets +1/+1 and has lifelink and "Whenever this creature deals combat damage to a player, draw a card."

Curse of the Forsaken

Enchant player
Whenever a creature attacks enchanted player, its controller gains 1 life.

Daxos of Meletis

Daxos can't be blocked by creatures with power 3 or greater.
Whenever Daxos deals combat damage to a player, exile the top card of that player's library. You gain life equal to that card's mana value. Until end of turn, you may cast that card and you may spend mana as though it were mana of any color to cast that spell.

Precinct Captain

First strike
Whenever this creature deals combat damage to a player, create a 1/1 white Soldier creature token.

Nightveil Sprite

Flying
Whenever this creature attacks, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Balshan Beguiler

Whenever this creature deals combat damage to a player, that player reveals the top two cards of their library. You choose one of those cards and put it into their graveyard.

Kitesail Skirmisher

Flying
Whenever this creature attacks, another target creature attacking the same player or planeswalker gains flying until end of turn.
Encore {4}{U} ({4}{U}, 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.)

Wingshield Agent

This creature enters with a shield counter on it. (If it would be dealt damage or destroyed, remove a shield counter from it instead.)
Whenever this creature attacks, up to one other target creature gains flying until end of turn.

Dovin, Grand Arbiter

+1: Until end of turn, whenever a creature you control deals combat damage to a player, put a loyalty counter on Dovin.
−1: Create a 1/1 colorless Thopter artifact creature token with flying. You gain 1 life.
−7: Look at the top ten cards of your library. Put three of them into your hand and the rest on the bottom of your library in a random order.

Bident of Thassa

Whenever a creature you control deals combat damage to a player, you may draw a card.
{1}{U}, {T}: Creatures your opponents control attack this turn if able.

Curse of Verbosity

Enchant player
Whenever enchanted player is attacked, you draw a card. Each opponent attacking that player does the same.

Storm Fleet Negotiator

Flying
Parley — Whenever this creature attacks, each player reveals the top card of their library. For each nonland card revealed this way, you create a Map token. Then each player draws a card. (A Map token is an artifact with "{1}, {T}, Sacrifice this token: Target creature you control explores. Activate only as a sorcery.")

Kitesail Corsair

This creature has flying as long as it's attacking.

Guild Thief

Whenever this creature deals combat damage to a player, put a +1/+1 counter on it.
Cunning Action — {3}{U}: This creature can't be blocked this turn.

Warkite Marauder

Flying
Whenever this creature attacks, target creature defending player controls loses all abilities and has base power and toughness 0/1 until end of turn.

Rhox Veteran

Battle cry (Whenever this creature attacks, each other attacking creature gets +1/+0 until end of turn.)
Whenever this creature attacks, tap target creature an opponent controls.

Jelenn Sphinx

Flying, vigilance
Whenever this creature attacks, other attacking creatures get +1/+1 until end of turn.

Library Larcenist

Whenever this creature attacks, draw a card.

Augury Adept

Whenever this creature deals combat damage to a player, reveal the top card of your library and put that card into your hand. You gain life equal to its mana value.

Malcolm, Alluring Scoundrel

Flash
Flying
Whenever Malcolm deals combat damage to a player, put a chorus counter on it. Draw a card, then discard a card. If there are four or more chorus counters on Malcolm, you may cast the discarded card without paying its mana cost.

Phase Dolphin

Whenever this creature attacks, another target attacking creature can't be blocked this turn.

Brimaz, King of Oreskos

Vigilance
Whenever Brimaz attacks, create a 1/1 white Cat Soldier creature token with vigilance that's attacking.
Whenever Brimaz blocks a creature, create a 1/1 white Cat Soldier creature token with vigilance that's blocking that creature.

Geist of Saint Traft

Hexproof (This creature can't be the target of spells or abilities your opponents control.)
Whenever Geist of Saint Traft attacks, create a 4/4 white Angel creature token with flying that's tapped and attacking. Exile that token at end of combat.