Sleep

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

Brinelin, the Moon Kraken

When Brinelin, the Moon Kraken enters and whenever you cast a spell with mana value 6 or greater, you may return target nonland permanent to its owner's hand.
Partner (You can have two commanders if both have partner.)

Cancel

Stormtide Leviathan

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
All lands are Islands in addition to their other types.
Creatures without flying or islandwalk can't attack.

Aegis Turtle

Mind Control

Enchant creature
You control enchanted creature.

Frozen Solid

Enchant creature
Enchanted creature doesn't untap during its controller's untap step.
When enchanted creature is dealt damage, destroy it.

Cerulean Drake

Flying
Protection from red (This creature can't be blocked, targeted, dealt damage, enchanted, or equipped by anything red.)
Sacrifice Cerulean Drake: Counter target spell that targets you.

Azure Drake

Imprisoned in the Moon

Enchant creature, land, or planeswalker
Enchanted permanent is a colorless land with "{T}: Add {C}" and loses all other card types and abilities.

Inkwell Leviathan

Trample
Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
Shroud (This creature can't be the target of spells or abilities.)

Counterspell

Moon Heron

Kraken's Eye

Whenever a player casts a blue spell, you may gain 1 life.

Island

Sapphire Medallion

Blue spells you cast cost {1} less to cast.

Skywinder Drake

Flying
Skywinder Drake can block only creatures with flying.

Dragon Turtle

Flash
Drag Below — When Dragon Turtle enters, tap it and up to one target creature an opponent controls. They don't untap during their controllers' next untap steps.