How to Increase freezing Pulse dps

Currently I have made it to Act 3 merciless with my freeze pulse witch however my dps is only at about 400 with lmp.
I also have got cold pen and mana leech linked to it.

Also I have a combo of crit chance and spell damge, would it be best to just go either crit or pure spell damage with crit as a bonus.

I also have cold snap + trap + increased AOE + ele prolif

Any suggestions on how to increase my DPS would be greatly appreciated

Try swapping cold pen for an added lightning gem. That way when you crit you can shock stack your enemies.

ok Thanks for that, I'll give it a go and see if it helps