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 - $1.90
Lightly Played - $1.80
Played - $1.40
Heavily Played - $1.20
Damaged - $1.00
Near Mint Non-English - $1.90
Lightly Played Non-English - $1.80
Played Non-English - $1.40
Heavily Played Non-English - $1.20
Damaged Non-English - $1.00