Geth's Grimoire

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

Megrim

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

Hypnotic Specter

Flying
Whenever this creature deals damage to an opponent, that player discards a card at random.

Wash Out

Return all permanents of the color of your choice to their owners' hands.

Go Blank

Target player discards two cards. Then exile that player's graveyard.

Drowned Catacomb

This land enters tapped unless you control an Island or a Swamp.
{T}: Add {U} or {B}.

Necrogen Spellbomb

{B}, Sacrifice this artifact: Target player discards a card.
{1}, Sacrifice this artifact: Draw a card.

Warped Devotion

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

Recoil

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

Swamp

Cephalid Looter

{T}: Target player draws a card, then discards a card.

Boomerang

Return target permanent to its owner's hand.

Aether Burst

Return up to X target creatures to their owners' hands, where X is one plus the number of cards named Aether Burst in all graveyards as you cast this spell.

Aether Spellbomb

{U}, Sacrifice this artifact: Return target creature to its owner's hand.
{1}, Sacrifice this artifact: Draw a card.