Instigator

{1}{B}{B}, {T}, Discard a card: Creatures target player controls attack this turn if able.

Stampede Driver

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

Bog Witch

Trickster Mage

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

Waterfront Bouncer

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

Cackling Witch

{X}{B}, {T}, Discard a card: Target creature gets +X/+0 until end of turn.

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.

Rushwood Herbalist

{G}, {T}, Discard a card: Regenerate target creature.

Greel, Mind Raker

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

Plague Witch

{B}, {T}, Discard a card: Target creature gets -1/-1 until end of turn.

Stronghold Biologist

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

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.)

Llanowar Mentor

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

Alexi, Zephyr Mage

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

Deepwood Elder

{X}{G}{G}, {T}, Discard a card: X target lands become Forests until end of turn.

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.

Jolrael, Empress of Beasts

{2}{G}, {T}, Discard two cards: All lands target player controls become 3/3 creatures until end of turn. They're still lands.

Stronghold Machinist

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

Diplomatic Escort

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

Undertaker

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

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.

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.

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.

Damia, Sage of Stone

Deathtouch
Skip your draw step.
At the beginning of your upkeep, if you have fewer than seven cards in hand, draw cards equal to the difference.

Dawnstrider

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

Notorious Assassin

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