Spirit Shackle, which I think makes more sense with its Japanese name Shadow Stitching. The arrow's trajectory is like a needle binding the opponent to the battle field. Good chance of it being a Thousand Waves retype with 90 BP.
Shadow Claw is probable, and I'd bet on Phantom Force too. If it ends up more defensive Seeding with PF to stall would be gimmicky fun. It will also probably get Shadow Ball but it's likely to lean physical.
Maybe it can turn invisible. It can conceal its presence completely, at least. Time to play The Hidden.