Spellcasting-slowers? Do they Stack?

Well i saw a build yesterday that intrigued me and it used Arcane conundrum and concussion shot.
Basdically you use arcane conundrum on the monk then he uses a hex removal then you use concussion shot
The elite used was puninshing shot but i was thinking of subbing that out with Migraine IF it were to stack with the "daze" from concussion shot.
Does it? and if yes in wich way?

3x2=6
3+2=5
3x100%=3
3+100%(of 3)= 6

yeah they stack... but i don't see the point...

any spell over 1 sec u should have np interupting

Yes, but novadays the boon monks are swarming interupting RoF is quite hard. I tried this build with concusion + migraine. It is good, but not the best. Best one is w/me Skull crack (but its quite hard to interupt with it) + Arcane Conundrum....and then just use frenzy Monk is totaly dissabled.

That may very well have been me. I was running that build in RA that night.

As far as I am aware, the stacking cap on casting duration lengtheners is small enough that none of them effectively stack. The main point was/is to use Arcane to lengthen those quick monk spells so you can reasonably hit with Concussion, making everything interrupt then.

Oh and Skull Crack is horrible. Spending your elite on a skill that really does nothing unless it interrupts, but does not have any activation time (thus you have no control over when it fires). Just yuck.

Skull crack rocks. I assume that you have never used it before and only read the skill description. After awhile using it, you get a sense of the timing and it becomes much more fun to use.