Goliath Daydreamer

Whenever you cast an instant or sorcery spell from your hand, exile that card with a dream counter on it instead of putting it into your graveyard as it resolves.
Whenever this creature attacks, you may cast a spell from among cards you own in exile with dream counters on them without paying its mana cost.

Kongming, "Sleeping Dragon"

Sleep

Tap all creatures target player controls. Those creatures don't untap during that player's next untap step.

Sleeper Dart

When this artifact enters, draw a card.
{T}, Sacrifice this artifact: Target creature doesn't untap during its controller's next untap step.

Pillory of the Sleepless

Enchant creature
Enchanted creature can't attack or block.
Enchanted creature has "At the beginning of your upkeep, you lose 1 life."

Send to Sleep

Tap up to two target creatures.
Spell mastery — If there are two or more instant and/or sorcery cards in your graveyard, those creatures don't untap during their controllers' next untap steps.

Sleeping Potion

Enchant creature
When this Aura enters, tap enchanted creature.
Enchanted creature doesn't untap during its controller's untap step.
When enchanted creature becomes the target of a spell or ability, sacrifice this Aura.

Narcolepsy

Enchant creature
At the beginning of each upkeep, if enchanted creature is untapped, tap it.

Sleep Magic

Enchant creature
When this Aura enters, tap enchanted creature.
Enchanted creature doesn't untap during its controller's untap step.
When enchanted creature is dealt damage, sacrifice this Aura.

Charmed Sleep

Enchant creature
When this Aura enters, tap enchanted creature.
Enchanted creature doesn't untap during its controller's untap step.

Awaken the Sleeper

Gain control of target creature until end of turn. Untap that creature. It gains haste until end of turn. If it's equipped, you may destroy all Equipment attached to that creature.

Sigil of Sleep

Enchant creature
Whenever enchanted creature deals damage to a player, return target creature that player controls to its owner's hand.

Fear of Sleep Paralysis

Flying
Eerie — Whenever this creature or another enchantment you control enters and whenever you fully unlock a Room, tap up to one target creature and put a stun counter on it.
Stun counters can't be removed from permanents your opponents control. (They won't untap if they have stun counters.)

Stifle

Counter target activated or triggered ability. (Mana abilities can't be targeted.)

Sleep Paralysis

Savior of the Sleeping

Vigilance
Whenever an enchantment you control is put into a graveyard from the battlefield, put a +1/+1 counter on this creature.