sb/infi/ns takes 10 seconds to disappear in the shadows. Once in the shadows the sb/infi/ns will automatically teleport to and perf any enemy they choose within 1000 radius. Can not be used to enter a locked keep or tower.

so i have a question will be it inmpemented ? or no ?

No.

It's was a RR5 (SB) ability since 1.82 so it won't be available in stealth spec line.

Originally Shadowstrike was the SB RR5, Assassinate was the Infi RR5 and Remedy was the NS RR5. However, remedy turned out to be wicked OP vs assassin classes while shadowstrike/assassinate were entirely situational (IE your target had to be LDing or AFK for you to pull off) and thus totally useless. Eventually all assassin classes got remedy which is how it is on uth. I would much rather have remedy then shadowstrike or assassinate because any inf/sb/ns without remedy knows that you're free RPs to one who does have it.