[3.19.2] Cold Witch

hello all, dirty casual here,
really enjoying the game, can you rate or advice or this build? Am I on the right path?
I feel is really powerful, no challenges so far. some bosses I die a few times but just due to bad handling of spells and not knowing the incoming attacks at all.

I frostbite the groups, then main attack is glacial cascade and freezing pulse to freeze if possible. then vortex and cold snap are useful too.
I feel cold mastery and caster mastery are the only skills useful in the tree..?
Also I need to look up on how to do the cold damage recipes, this is a complex game...

http://www.pathofexile.com/account/view-profile/capitanpedos

does the game end in the last act or is there a new difficulty as in d2?

any way, thanks a have a good one,

Can't see your build on your profile since it is set to private.

Frost bomb is a good addition which reduces enemy cold res. Spell critical strike chance is good for cold spells since they freezes enemies and honestly the shattering of enemies is satsifying. You can also look into ways of generating power charges.

After the last act, there's a ton of content. Some would say that's the actual game. :)
Campaign is good but Maps, Atlas and the bosses are like main reason a lot of us still play this game tbh ;)