Control Magic

Enchant creature
You control enchanted creature.

Sapphire Medallion

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

Copy Artifact

You may have this enchantment enter as a copy of any artifact on the battlefield, except it's an enchantment in addition to its other types.

Serendib Efreet

Flying
At the beginning of your upkeep, this creature deals 1 damage to you.

Counterspell

Fountain of Youth

Island

Steal Artifact

Enchant artifact
You control enchanted artifact.

Vesuvan Doppelganger

You may have this creature enter as a copy of any creature on the battlefield, except it doesn't copy that creature's color and it has "At the beginning of your upkeep, you may have this creature become a copy of target creature, except it doesn't copy that creature's color and it has this ability."

Clone

You may have this creature enter as a copy of any creature on the battlefield.

Flying Men

Force of Will

You may pay 1 life and exile a blue card from your hand rather than pay this spell's mana cost.
Counter target spell.

Maze of Ith

{T}: Untap target attacking creature. Prevent all combat damage that would be dealt to and dealt by that creature this turn.

Tidal Warrior

{T}: Target land becomes an Island until end of turn.

Braingeyser

Fellwar Stone

{T}: Add one mana of any color that a land an opponent controls could produce.

Mahamoti Djinn

Flying (This creature can't be blocked except by creatures with flying or reach.)

Lord of Atlantis

Other Merfolk get +1/+1 and have islandwalk. (They can't be blocked as long as defending player controls an Island.)