Ghostly Pilferer

Whenever this creature becomes untapped, you may pay {2}. If you do, draw a card.
Whenever an opponent casts a spell from anywhere other than their hand, draw a card.
Discard a card: This creature can't be blocked this turn.

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 and it deals 1 damage to each opponent.
{R}: Target Shark gains trample until end of turn.

Glint-Horn Buccaneer

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

Psychic Frog

Whenever this creature deals combat damage to a player or planeswalker, draw a card.
Discard a card: Put a +1/+1 counter on this creature.
Exile three cards from your graveyard: This creature gains flying until end of turn.

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.

Oblivion Crown

Flash (You may cast this spell any time you could cast an instant.)
Enchant creature
Enchanted creature has "Discard a card: This creature gets +1/+1 until end of turn."

Psychatog

Discard a card: This creature gets +1/+1 until end of turn.
Exile two cards from your graveyard: This creature gets +1/+1 until end of turn.

Trespasser il-Vec

Discard a card: This creature gains shadow until end of turn. (It can block or be blocked by only creatures with shadow.)

Emrakul, the Promised End

This spell costs {1} less to cast for each card type among cards in your graveyard.
When you cast this spell, you gain control of target opponent during that player's next turn. After that turn, that player takes an extra turn.
Flying, trample, protection from instants

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.)

Magmakin Artillerist

Whenever you discard one or more cards, this creature deals that much damage to each opponent.
Cycling {1}{R} ({1}{R}, Discard this card: Draw a card.)
When you cycle this card, it deals 1 damage to each opponent.

Land's Edge

Discard a card: If the discarded card was a land card, this enchantment deals 2 damage to target player or planeswalker. Any player may activate this ability.

Prognostic Sphinx

Flying
Discard a card: This creature gains hexproof until end of turn. Tap it.
Whenever this creature attacks, scry 3.

Hell Mongrel

Discard a card: This creature gets +1/+1 until end of turn.
Madness {2}{B} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

Captain Howler, Sea Scourge

Ward—{2}, Pay 2 life.
Whenever you discard one or more cards, target creature gets +2/+0 until end of turn for each card discarded this way. Whenever that creature deals combat damage to a player this turn, you draw a card.

Green Goblin, Nemesis

Flying
Whenever you discard a nonland card, put a +1/+1 counter on target Goblin you control.
Whenever you discard a land card, create a tapped Treasure token.

Thalakos Drifters

Oona's Prowler

Flying
Discard a card: This creature gets -2/-0 until end of turn. Any player may activate this ability.

Aquamoeba

Discard a card: Switch this creature's power and toughness until end of turn.

Olivia's Dragoon

Discard a card: This creature gains flying until end of turn.

Aeromoeba

Flying
Discard a card: Switch this creature's power and toughness until end of turn.

Faerie Macabre

Flying
Discard this card: Exile up to two target cards from graveyards.

Cryptcaller Chariot

Menace
Whenever you discard one or more cards, create that many tapped 2/2 black Zombie creature tokens.
Crew 2

Putrid Imp

Discard a card: This creature gains flying until end of turn.
Threshold — As long as seven or more cards are in your graveyard, this creature gets +1/+1 and can't block.

Grotesque Hybrid

Whenever this creature deals combat damage to a creature, destroy that creature. It can't be regenerated.
Discard a card: This creature gains flying and protection from green and from white until end of turn.

Fleshgrafter

Discard an artifact card: This creature gets +2/+2 until end of turn.

Deal Damage

Deal Damage deals 4 damage to any target.
Gotcha — If an opponent says "deal" or "damage," you may say "Gotcha!" When you do, return Deal Damage from your graveyard to your hand.

Flameblade Adept

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

Cabal Initiate

Discard a card: This creature gains lifelink until end of turn.
Threshold — This creature gets +1/+2 as long as seven or more cards are in your graveyard.

Skirge Familiar

Volrath's Dungeon

Pay 5 life: Destroy this enchantment. Any player may activate this ability but only during their turn.
Discard a card: Target player puts a card from their hand on top of their library. Activate only as a sorcery.

Cunning Survivor

Whenever you cycle or discard a card, this creature gets +1/+0 until end of turn and can't be blocked this turn.

Cephalid Inkshrouder

Discard a card: This creature gains shroud until end of turn and can't be blocked this turn. (A creature with shroud can't be the target of spells or abilities.)

Feast of Sanity

Whenever you discard a card, this enchantment deals 1 damage to any target and you gain 1 life.