Harvest Mage

{G}, {T}, Discard a card: Until end of turn, if you tap a land for mana, it produces one mana of a color of your choice instead of any other type and amount.

Trickster Mage

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

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.

Netter en-Dal

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

Deepwood Drummer

{G}, {T}, Discard a card: Target creature gets +2/+2 until end of turn.

Notorious Assassin

{2}{B}, {T}, Discard a card: Destroy target nonblack creature. It can't be regenerated.

Stampede Driver

{1}{G}, {T}, Discard a card: Creatures you control get +1/+1 and gain trample until end of turn.

Greenseeker

{G}, {T}, Discard a card: Search your library for a basic land card, reveal it, put it into your hand, then shuffle.

Mageta the Lion

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

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.

Alexi, Zephyr Mage

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

Diplomatic Escort

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

Silverglade Pathfinder

{1}{G}, {T}, Discard a card: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Llanowar Mentor

{G}, {T}, Discard a card: Create a 1/1 green Elf Druid creature token named Llanowar Elves. It has "{T}: Add {G}."

Seismic Mage

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

Stronghold Biologist

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

Undertaker

{B}, {T}, Discard a card: Return target creature card from your graveyard to your hand.

Latulla, Keldon Overseer

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

Hammer Mage

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

Devout Witness

{1}{W}, {T}, Discard a card: Destroy target artifact or enchantment.

Stronghold Machinist

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

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.

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.

Dawnstrider

{G}, {T}, Discard a card: Prevent all combat damage that would be dealt this turn.

Arc Mage

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

Greel, Mind Raker

{X}{B}, {T}, Discard two cards: Target player discards X cards at random.

Divining Witch

{1}{B}, {T}, Discard a card: Choose a card name. Exile the top six cards of your library, then reveal cards from the top of your library until you reveal a card with the chosen name. Put that card into your hand and exile all other cards revealed this way.

Waterfront Bouncer

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

Avenger en-Dal

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