As long as your devotion to blue is less than five, Thassa isn't a creature. (Each U in the mana costs of permanents you control counts toward your devotion to blue.)
At the beginning of your upkeep, scry 1.
1U: Target creature you control can't be blocked this turn.
Near Mint - $0.50
Lightly Played - $0.40
Moderately Played - $0.40
Heavily Played - $0.30
Damaged - $0.30
Near Mint Spanish - $0.50
Lightly Played Spanish - $0.40
Moderately Played Spanish - $0.40
Heavily Played Spanish - $0.30
Damaged Spanish - $0.30