my thoughts would every skill, and every regular attack would be a dummy being knockedback etc. and if the missle/dummy goes into the range of the slow-mo area, then set the missle speed to 1/2 in the knockback etc.
but to do all that work for 1 skill seems like well, to much work. if your map was based around time shifting and matrix like gameplay then it might work out nicely. but for 1 skill, i personally would pass.