Merciless Harlequin

an Assassin deals combat damage — 212 cards in the game can cause this (Merciless Harlequin is one).

When Merciless Harlequin deals combat damage:

1. Layla Hassan — brings a card back
2. Ezio, Blade of Vengeance — draws you 1 card
3. Etrata, Deadly Fugitive — triggers
4. Jacob Frye — exiles a card from your graveyard

an Assassin attacks — 212 cards in the game can cause this (Merciless Harlequin is one).

When Merciless Harlequin attacks:

1. The Revelations of Ezio — puts a counter on a permanent
2. Origin of the Hidden Ones — makes a token

an Assassin creature it grants types to — 219 cards in the game can cause this.

1. Reaper's Scythe — Reaper's Scythe gives Merciless Harlequin an extra creature type

218 other cards cause it too. These are the ones with the most connections.

life is lost — 3,160 cards in the game can cause this (Merciless Harlequin is one).

When Merciless Harlequin makes a player lose life:

1. The Master of Lake-town — mills a card
2. Intermediate Chirography — puts a counter on a creature
3. Vilis, Broker of Blood — draws you that many cards
4. Vengeful Warchief — puts a +1/+1 counter on itself
5. Wax-Wane Witness — gets +1/+0
6. Oath of Lim-Dûl — sacrifices an enchantment
7. Marina Vendrell's Grimoire — triggers
8. Lich's Mastery — triggers
9. Lich's Tomb — sacrifices a permanent
10. Gonti's Machinations — puts a counter on a permanent you control

46 other cards care about it too. These are the ones with the most connections.

a card is drawn — 3,815 cards in the game can cause this (Merciless Harlequin is one).

When Merciless Harlequin makes a player draw a card:

1. Aether Syphon — mills a card
2. Temmet, Naktamun's Will — gives +1/+1
3. Niv-Mizzet, Parun — deals 1 damage
4. The Locust God — makes a token
5. Starving Revenant — makes each opponent lose 1 life
6. Diviner's Wand — gets +1/+1
7. Ominous Seas — puts a foreshadow counter on itself
8. Dream Trawler — gets +1/+0
9. Iron Man, Armored Avenger — puts a counter on a creature
10. The Astonishing Ant-Man — puts a +1/+1 counter on itself

57 other cards care about it too. These are the ones with the most connections.

a Human enters the battlefield — 4,639 cards in the game can cause this (Merciless Harlequin is one).

When Merciless Harlequin enters:

1. General Kudro of Drannith — hits a graveyard
2. Heronblade Elite — puts a +1/+1 counter on itself
3. Kyler, Sigardian Emissary — puts a +1/+1 counter on itself
4. Thalia's Lieutenant — puts a +1/+1 counter on itself
5. Champion of the Parish — puts a +1/+1 counter on itself
6. Captain of the Mists — untaps itself
7. Erkenbrand, Lord of Westfold — gives +1/+0
8. Beregond of the Guard — gives +1/+1
9. Théoden, King of Rohan — grants double strike
10. Lossarnach Captain — taps a creature an opponent controls

2 other cards care about it too. These are the ones with the most connections.

anything attacks — 17,934 cards in the game can cause this (Merciless Harlequin is one).

When Merciless Harlequin attacks:

1. Far Fortune, End Boss — deals 1 damage
2. Grim Javelineer — gives +1/+0
3. Invisible Woman — triggers
4. Caesar, Legion's Emperor — sacrifices a creature
5. Guide of Souls — triggers
6. Campsite Cuisine — sacrifices a Food
7. Gossip's Talent — triggers
8. Banon, the Returners' Leader — draws and discards
9. Toph, Earthbending Master — puts a counter on a permanent
10. Three Dog, Galaxy News DJ — sacrifices an Aura

113 other cards care about it too. These are the ones with the most connections.

a creature attacks — 17,934 cards in the game can cause this (Merciless Harlequin is one).

When Merciless Harlequin attacks:

1. Adaptive Omnitool — searches a library
2. Anthem of Rakdos — gives +2/+0
3. Kindred Discovery — draws you 1 card
4. Invasion of New Capenna // Holy Frazzle-Cannon — puts counters on a permanent
5. Chorale of the Void — brings a card back
6. Saw — sacrifices a creature

186 other cards care about it too. These are the ones with the most connections.

a creature blocks — 17,934 cards in the game can cause this (Merciless Harlequin is one).

1. Tide of War — When Merciless Harlequin blocks, Tide of War sacrifices a creature

27 other cards care about it too. These are the ones with the most connections.

a creature enters the battlefield — 19,800 cards in the game can cause this (Merciless Harlequin is one).

When Merciless Harlequin enters:

1. Slash, Reptile Rampager — deals 2 damage
2. Ray Fillet, Wave Warrior — puts a counter on itself
3. The Neutrinos — gets +1/+0
4. Wingnut, Bat on the Belfry — grants flying, haste and menace
5. Aetherstorm Roc — puts a counter on a permanent you control
6. Raphael, Most Attitude — exiles a card from your library

308 other cards care about it too. These are the ones with the most connections.

anything enters the battlefield — 26,499 cards in the game can cause this (Merciless Harlequin is one).

1. Prowl, Stoic Strategist // Prowl, Pursuit Vehicle — When Merciless Harlequin enters, Prowl, Stoic Strategist // Prowl, Pursuit Vehicle puts a +1/+1 counter on itself

43 other cards care about it too. These are the ones with the most connections.