+Segovia (4)
Noncreature spells you cast have convoke. (Your creatures can help cast those spells. Each creature you tap while casting a noncreature spell pays for or one mana of that creature's color.)
At the beginning of your end step, untap up to four target creatures.
(As a Siege enters, choose an opponent to protect it. You and others can attack it. When it's defeated, exile it, then cast it transformed.)
When Invasion of Segovia enters, create two 1/1 blue Kraken creature tokens with trample.
Flying, vigilance
Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
Gatherer works better in the Companion app!