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 - $1.20
Lightly Played - $0.90
Moderately Played - $0.80
Heavily Played - $0.70
Damaged - $0.60
Near Mint Spanish - $1.20
Lightly Played Spanish - $0.90
Moderately Played Spanish - $0.80
Heavily Played Spanish - $0.70
Damaged Spanish - $0.60