Well, I actually did not have frost so I didn't check...
But everything that doesn't last 12 turns stacks.
Mind Freeze, Glacier, Flash Freeze...
Glacier lasts 6 turns...good enough since the others last 2 or 3
I never made use of Mind Freeze. Seemed like a waste of Action Bar space when you have Flash Freeze. I'm not sure why would you want to stack either of them though. Anyways, I repeat my point that Glacier should be your primary attack if you're playing as Cold Hydro.
SLiPCoR, 1 point doesn't suffice because Flash Freeze can be equipped 2 times when 4 points are used into it. It also costs nothing in such an instance
Excellent guide, but I recommend to use regulate lvl2 instead of vapor cannon, because it will give you 10 focus per turn for 11 turns instead of 12 focus per turn for 3 turns.