(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 the battlefield, create two 1/1 blue kraken creature tokens with trample.
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caetus, sea tyrant of segovia
noncreature spells you cast have convoke. (your creatures can help cast those spells. each creature you tap while casting a noncreature spell pays for 1 or one mana of that creature's color.)
at the beginning of your end step, untap up to four target creatures.