Geth's Grimoire

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

Cephalid Looter

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

Warped Devotion

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

Island

Hypnotic Specter

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

Megrim

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

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.

Necrogen Spellbomb

{B}, Sacrifice Necrogen Spellbomb: Target player discards a card.
{1}, Sacrifice Necrogen Spellbomb: Draw a card.

Recoil

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

Drowned Catacomb

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

Boomerang

Return target permanent to its owner's hand.

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.

Aether Spellbomb

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