Theorycrafting Question

Hey all,

I am wanting to make vortex traps (since I haven't really seen that skill used as a trap yet).

Currently, I am thinking of the best gems for it. The last 2 are really difficult for me to choose though. Can someone help me please, if they have any experience with vortex?

4-link: vortex, trap, cluster traps, trap and mine damage

The last 2 are difficult for me. It will be between any of these: added cold, cold pen, hypothermia, inc aoe/conc effect.

Currently, I am using cold pen and hypothermia, but I have a feeling conc effect would be insanely good for bosses.

Thanks!