Windfall

Each player discards their hand, then draws cards equal to the greatest number of cards a player discarded this way.

Waterfront Bouncer

{U}, {T}, Discard a card: Return target creature to its owner's hand.

Arc Mage

{2}{R}, {T}, Discard a card: Arc Mage deals 2 damage divided as you choose among one or two targets.

Ghost Tactician

{W}, {T}, Discard a card: Creatures you control get +1/+0 until end of turn.

Bola Warrior

{R}, {T}, Discard a card: Target creature can't block this turn.

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.

Charm Peddler

{W}, {T}, Discard a card: The next time a source of your choice would deal damage to target creature this turn, prevent that damage.

Dreamscape Artist

{2}{U}, {T}, Discard a card, Sacrifice a land: Search your library for up to two basic land cards, put them onto the battlefield, then shuffle.

Shabraz, the Skyshark

Partner with Brallin, Skyshark Rider
Flying
Whenever you draw a card, put a +1/+1 counter on Shabraz, the Skyshark and you gain 1 life.
{W/U}: Target Human gains flying until end of turn.

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.

Icatian Crier

{1}{W}, {T}, Discard a card: Create two 1/1 white Citizen creature tokens.

Seismic Mage

{2}{R}, {T}, Discard a card: Destroy target land.

Alexi, Zephyr Mage

{X}{U}, {T}, Discard two cards: Return X target creatures to their owners' hands.

Balloon Peddler

{U}, {T}, Discard a card: Target creature gains flying until end of turn.

Sliversmith

{1}, {T}, Discard a card: Create a 1/1 colorless Sliver artifact creature token named Metallic Sliver.

Stronghold Machinist

{U}{U}, {T}, Discard a card: Counter target noncreature spell.

Mercurial Chemister

{U}, {T}: Draw two cards.
{R}, {T}, Discard a card: Mercurial Chemister deals damage to target creature equal to the discarded card's mana value.

Netter en-Dal

{W}, {T}, Discard a card: Target creature can't attack this turn.

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.

Zirda, the Dawnwaker

Companion — Each permanent card in your starting deck has an activated ability. (If this card is your chosen companion, you may put it into your hand from outside the game for {3} as a sorcery.)
Abilities you activate that aren't mana abilities cost {2} less to activate. This effect can't reduce the mana in that cost to less than one mana.
{1}, {T}: Target creature can't block this turn.

Goldmeadow Lookout

{W}, {T}, Discard a card: Create a 1/1 white Kithkin Soldier creature token named Goldmeadow Harrier. It has "{W}, {T}: Tap target creature."

Flowstone Channeler

{1}{R}, {T}, Discard a card: Target creature gets +1/-1 and gains haste until end of turn.

Stronghold Biologist

{U}{U}, {T}, Discard a card: Counter target creature spell.

Cloudseeder

Flying
{U}, {T}, Discard a card: Create a 1/1 blue Faerie creature token named Cloud Sprite. It has flying and "Cloud Sprite can block only creatures with flying."

Trickster Mage

{U}, {T}, Discard a card: You may tap or untap target artifact, creature, or land.

Mageta the Lion

{2}{W}{W}, {T}, Discard two cards: Destroy all creatures except for Mageta the Lion. Those creatures can't be regenerated.

Cho-Arrim Alchemist

{1}{W}{W}, {T}, Discard a card: The next time a source of your choice would deal damage to you this turn, prevent that damage. You gain life equal to the damage prevented this way.

Avenger en-Dal

{2}{W}, {T}, Discard a card: Exile target attacking creature. Its controller gains life equal to its toughness.

Toymaker

{1}, {T}, Discard a card: Target noncreature artifact becomes an artifact creature with power and toughness each equal to its mana value until end of turn. (It retains its abilities.)

Hammer Mage

{X}{R}, {T}, Discard a card: Destroy all artifacts with mana value X or less.

Overtaker

{3}{U}, {T}, Discard a card: Untap target creature and gain control of it until end of turn. That creature gains haste until end of turn.

Tolarian Sentinel

Flying
{U}, {T}, Discard a card: Return target permanent you control to its owner's hand.

Diplomatic Escort

{U}, {T}, Discard a card: Counter target spell or ability that targets a creature.

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.

Sparkspitter

{R}, {T}, Discard a card: Create a 3/1 red Elemental creature token named Spark Elemental. It has trample, haste, and "At the beginning of the end step, sacrifice Spark Elemental."

Latulla, Keldon Overseer

{X}{R}, {T}, Discard two cards: Latulla, Keldon Overseer deals X damage to any target.

Jaya Ballard, Task Mage

{R}, {T}, Discard a card: Destroy target blue permanent.
{1}{R}, {T}, Discard a card: Jaya Ballard, Task Mage deals 3 damage to any target. A creature dealt damage this way can't be regenerated this turn.
{5}{R}{R}, {T}, Discard a card: Jaya Ballard deals 6 damage to each creature and each player.

Kris Mage

{R}, {T}, Discard a card: Kris Mage deals 1 damage to any target.

Teferi's Ageless Insight

If you would draw a card except the first one you draw in each of your draw steps, draw two cards instead.

Tonic Peddler

{W}, {T}, Discard a card: Target player gains 3 life.

Reconnaissance Mission

Whenever a creature you control deals combat damage to a player, you may draw a card.
Cycling {2} ({2}, Discard this card: Draw a card.)

Firefright Mage

{1}{R}, {T}, Discard a card: Target creature can't be blocked this turn except by artifact creatures and/or red creatures.

Shark Typhoon

Whenever you cast a noncreature spell, create an X/X blue Shark creature token with flying, where X is that spell's mana value.
Cycling {X}{1}{U} ({X}{1}{U}, Discard this card: Draw a card.)
When you cycle Shark Typhoon, create an X/X blue Shark creature token with flying.

Brallin, Skyshark Rider

Partner with Shabraz, the Skyshark (When this creature enters the battlefield, 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.