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 - £1.40
Lightly Played - £1.20
Moderately Played - £1.00
Heavily Played - £0.70
Damaged - £0.50
Near Mint Non English - £1.40
Lightly Played Non English - £1.20
Moderately Played Non English - £1.00
Heavily Played Non English - £0.70
Damaged Non English - £0.50