Archfiend of Ifnir

Flying
Whenever you cycle or discard another card, put a -1/-1 counter on each creature your opponents control.
Cycling {2} ({2}, Discard this card: Draw a card.)

Glint-Horn Buccaneer

Haste
Whenever you discard a card, Glint-Horn Buccaneer deals 1 damage to each opponent.
{1}{R}, Discard a card: Draw a card. Activate only if Glint-Horn Buccaneer is attacking.

Brallin, Skyshark Rider

Partner with Shabraz, the Skyshark (When this creature enters, target player may put Shabraz into their hand from their library, then shuffle.)
Whenever you discard a card, put a +1/+1 counter on Brallin, Skyshark Rider and it deals 1 damage to each opponent.
{R}: Target Shark gains trample until end of turn.

Spirit Cairn

Whenever a player discards a card, you may pay {W}. If you do, create a 1/1 white Spirit creature token with flying.

Bone Miser

Whenever you discard a creature card, create a 2/2 black Zombie creature token.
Whenever you discard a land card, add {B}{B}.
Whenever you discard a noncreature, nonland card, draw a card.

Drannith Stinger

Whenever you cycle another card, Drannith Stinger deals 1 damage to each opponent.
Cycling {1} ({1}, Discard this card: Draw a card.)

Crystalline Resonance

Whenever you cycle a card, you may have Crystalline Resonance become a copy of another target permanent until your next turn, except it has this ability.

Surly Badgersaur

Whenever you discard a creature card, put a +1/+1 counter on Surly Badgersaur.
Whenever you discard a land card, create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")
Whenever you discard a noncreature, nonland card, Surly Badgersaur fights up to one target creature you don't control.

Flameblade Adept

Menace
Whenever you cycle or discard a card, Flameblade Adept gets +1/+0 until end of turn.

Faith of the Devoted

Whenever you cycle or discard a card, you may pay {1}. If you do, each opponent loses 2 life and you gain 2 life.

Wharf Infiltrator

Skulk (This creature can't be blocked by creatures with greater power.)
Whenever Wharf Infiltrator deals combat damage to a player, you may draw a card. If you do, discard a card.
Whenever you discard a creature card, you may pay {2}. If you do, create a 3/2 colorless Eldrazi Horror creature token.

Invigorating Boon

Whenever a player cycles a card, you may put a +1/+1 counter on target creature.

Astral Drift

Whenever you cycle Astral Drift or cycle another card while Astral Drift is on the battlefield, you may exile target creature. If you do, return that card to the battlefield under its owner's control at the beginning of the next end step.
Cycling {2}{W} ({2}{W}, Discard this card: Draw a card.)

Lazotep Chancellor

Whenever you discard a card, you may pay {1}. If you do, amass Zombies 2. (Put two +1/+1 counters on an Army you control. It's also a Zombie. If you don't control an Army, create a 0/0 black Zombie Army creature token first.)

Drannith Healer

Whenever you cycle another card, you gain 1 life.
Cycling {1} ({1}, Discard this card: Draw a card.)

Flourishing Fox

Whenever you cycle another card, put a +1/+1 counter on Flourishing Fox.
Cycling {1} ({1}, Discard this card: Draw a card.)

Feast of Sanity

Whenever you discard a card, Feast of Sanity deals 1 damage to any target and you gain 1 life.

Savai Thundermane

Whenever you cycle a card, you may pay {2}. When you do, Savai Thundermane deals 2 damage to target creature and you gain 2 life.

Curator of Mysteries

Flying
Whenever you cycle or discard another card, scry 1.
Cycling {U} ({U}, Discard this card: Draw a card.)

Unpredictable Cyclone

If a cycling ability of another nonland card would cause you to draw a card, instead exile cards from the top of your library until you exile a card that shares a card type with the cycled card. You may cast that card without paying its mana cost. Then put the exiled cards that weren't cast this way on the bottom of your library in a random order.
Cycling {2} ({2}, Discard this card: Draw a card.)

Drake Haven

Whenever you cycle or discard a card, you may pay {1}. If you do, create a 2/2 blue Drake creature token with flying.

Astral Slide

Whenever a player cycles a card, you may exile target creature. If you do, return that card to the battlefield under its owner's control at the beginning of the next end step.

Valiant Rescuer

Whenever you cycle another card for the first time each turn, create a 1/1 white Human Soldier creature token.
Cycling {2} ({2}, Discard this card: Draw a card.)

Lightning Rift

Whenever a player cycles a card, you may pay {1}. If you do, Lightning Rift deals 2 damage to any target.

Ruthless Sniper

Whenever you cycle or discard a card, you may pay {1}. If you do, put a -1/-1 counter on target creature.

Rielle, the Everwise

Rielle, the Everwise gets +1/+0 for each instant and sorcery card in your graveyard.
Whenever you discard one or more cards for the first time each turn, draw that many cards.

Escape Protocol

Whenever you cycle a card, you may pay {1}. When you do, exile target artifact or creature you control, then return it to the battlefield under its owner's control.