Null Brooch

{2}, {T}, Discard your hand: Counter target noncreature spell.

Saproling Cluster

{1}, Discard a card: Create a 1/1 green Saproling creature token. Any player may activate this ability.

Vengeful Dreams

As an additional cost to cast this spell, discard X cards.
Exile X target attacking creatures.

Yasharn, Implacable Earth

When Yasharn enters, search your library for a basic Forest card and a basic Plains card, reveal those cards, put them into your hand, then shuffle.
Players can't pay life or sacrifice nonland permanents to cast spells or activate abilities.

Fa'adiyah Seer

{T}: Draw a card and reveal it. If it isn't a land card, discard it.

Krosan Tusker

Cycling {2}{G} ({2}{G}, Discard this card: Draw a card.)
When you cycle Krosan Tusker, you may search your library for a basic land card, reveal that card, put it into your hand, then shuffle. (Do this before you draw.)

Diamond Lion

{T}, Discard your hand, Sacrifice Diamond Lion: Add three mana of any one color. Activate only as an instant.

Bag of Holding

Whenever you discard a card, exile that card from your graveyard.
{2}, {T}: Draw a card, then discard a card.
{4}, {T}, Sacrifice Bag of Holding: Return all cards exiled with Bag of Holding to their owner's hand.

The Underworld Cookbook

{T}, Discard a card: Create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this artifact: You gain 3 life.")
{4}, {T}, Sacrifice The Underworld Cookbook: Return target creature card from your graveyard to your hand.

Abolish

You may discard a Plains card rather than pay this spell's mana cost.
Destroy target artifact or enchantment.

Pegasus Refuge

{2}, Discard a card: Create a 1/1 white Pegasus creature token with flying.

Peace of Mind

Dismantling Wave

For each opponent, destroy up to one target artifact or enchantment that player controls.
Cycling {6}{W}{W} ({6}{W}{W}, Discard this card: Draw a card.)
When you cycle Dismantling Wave, destroy all artifacts and enchantments.

Confessor

Whenever a player discards a card, you may gain 1 life.

Snag

You may discard a Forest card rather than pay this spell's mana cost.
Prevent all combat damage that would be dealt by unblocked creatures this turn.

Balancing Act

Each player chooses a number of permanents they control equal to the number of permanents controlled by the player who controls the fewest, then sacrifices the rest. Each player discards cards the same way.

Ayula's Influence

Discard a land card: Create a 2/2 green Bear creature token.

Rites of Spring

Discard any number of cards. Search your library for up to that many basic land cards, reveal them, put them into your hand, then shuffle.

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.

Magus of the Balance

{4}{W}, {T}, Sacrifice Magus of the Balance: Each player chooses a number of lands they control equal to the number of lands controlled by the player who controls the fewest, then sacrifices the rest. Players discard cards and sacrifice creatures the same way.