Seat of the Synod

Illusory Angel

Cast this spell only if you've cast another spell this turn.
Flying

Serum Visions

Deliberate

Phantasmal Bear

When Phantasmal Bear becomes the target of a spell or ability, sacrifice it.

Vapor Snag

Return target creature to its owner's hand. Its controller loses 1 life.

Krovikan Mist

Flying
Krovikan Mist's power and toughness are each equal to the number of Illusions on the battlefield.

Halimar Depths

Halimar Depths enters tapped.
When Halimar Depths enters, look at the top three cards of your library, then put them back in any order.
{T}: Add {U}.

Lord of the Unreal

Illusion creatures you control get +1/+1 and have hexproof. (They can't be the targets of spells or abilities your opponents control.)

Aetherize

Return all attacking creatures to their owner's hand.

Counterspell

Island

Phantasmal Dragon

Flying
When Phantasmal Dragon becomes the target of a spell or ability, sacrifice it.

Phantasmal Image

You may have Phantasmal Image enter as a copy of any creature on the battlefield, except it's an Illusion in addition to its other types and it has "When this creature becomes the target of a spell or ability, sacrifice it."