storm reaper vs phantom slash

Which is better invincibility skill for dual sword users?
I plan to keep them at lvl 1 only

 

If you're only going for invincibility, go with phantom, easier to control and has freeze effect for bosses like WW.

 

phantom slash.

it's faster,easier to execute,has longer invincible frame,has more usability to boss with "freeze" as weakness,and you can control it.

storm reaper just make you back flip stylishly to a ditch during sky arena.

they both have same mp cost.

 

Thanks