Swamp

Megrim

Whenever an opponent discards a card, Megrim deals 2 damage to that player.

Warped Devotion

Whenever a permanent is returned to a player's hand, that player discards a card.

Sway of Illusion

Any number of target creatures become the color of your choice until end of turn.
Draw a card.

Icy Manipulator

{1}, {T}: Tap target artifact, creature, or land.

Recoil

Return target permanent to its owner's hand. Then that player discards a card.

Eye of Nowhere

Return target permanent to its owner's hand.

Boomerang

Cowardice

Whenever a creature becomes the target of a spell or ability, return that creature to its owner's hand. (It won't be affected by the spell or ability.)

Seal of Removal

Sacrifice Seal of Removal: Return target creature to its owner's hand.

Geth's Grimoire

Whenever an opponent discards a card, you may draw a card.

Island

Rackling

At the beginning of each opponent's upkeep, Rackling deals X damage to that player, where X is 3 minus the number of cards in their hand.

Perplex

Counter target spell unless its controller discards their hand.
Transmute {1}{U}{B} ({1}{U}{B}, Discard this card: Search your library for a card with the same mana value as this card, reveal it, put it into your hand, then shuffle. Transmute only as a sorcery.)