Legendary Six Samurai - Shi En

Hi!

My opponent has a face up Shi En on his side of the field. I activate a quick spell card (during his turn) and he negates it with the effect of Shi En. He attacks and ends his turn.

I wanna activate dark hole now, since he already used Shi Ens effect but he says he can activate Shi Ens effect once more, since it s usable during each players turn, even if he already activated the effect during his turn.

if that is true, than what the difference between him and any other card that activates it s effect once per turn? (i.e. Fabled Raven, Blackwing - Gale the Whirlwind, etc..)

Thank you!

ok thanks a lot!