Iirc, it got the cast time added because when it didn't have one, NB were able to use it to teleport through closed keep doors when timed correctly with an enemy using the door (which was extremely heavily abused back then).

The other abilities couldn't do this because they have a "sprint" type of gap close where they push the caster across the ground to the target over a set duration, so the caster would collide with the wall/door if they tried to do the same thing with those abilities, but because teleport strike is an actual, "instant" teleport that doesn't require terrain and not a "sprint" or "push" that moves its caster across the terrain over a duration, it could ignore the obstacles and teleport the NB right through them into areas that the NB should not be allowed to have access to at that point in time.

I doubt this ability will ever get reverted to being instant cast again, it is too easy to abuse that interaction if it were to ever be reverted to being properly instant again. I would look to get it improved in another way to make it worth using with the cast time. Maybe something like:
- move the DoT component currently on the lotus fan morph to the base ability (make it single target)
- replace minor vulnerability with a unique debuff that increases damage done against monsters affected by it
The morphs would separate themselves via:
- Lotus fan (mag) becomes AoE
- Ambush (stam) the DoT becomes stronger and also grants empower + minor berserk

I am not using this ability because of the castime. Just saying.

It contradicts with the whole point of the class imo. You are supposed to be fast, swift and deadly…but thats not possible with a frickin cast time😂