Hey, thanks for the guide.
Just can't get what's a benefit of making cold to fire convertion. Isn't freezing with cold should be better?
Pretty good question. Cold version gives us some good chills and freezes, but there are some problems when we compare to the fire version. I'd highlight accuracy, damage, and passive management.
First, If we change Effigon for another amulet (such as Pandemonius), we would then need to invest on accuracy, a problem we don't currently have. We could place Lycosidae, but we would lose the dual Cospri, losing damage. We could also keep Effigon, but we would waste its resistance penetration (maybe it's still a good option, though).
About elemental damage, we currently have all cold damage converted to fire damage, so we benefit from both cold and fire affixes and passives. By changing to cold, we would lose the multiplicative sources (as we would only rely on cold affixes).
Still about damage, we also need to talk about elemental penetration, something often not mentioned but it's something that makes the build shine. We have quite a lot on the fire versios: we can achieve 10+15+10+6+25+19 (boots enchant + Wise Oak + Effigon* + Heart of Flame* + Wave of Conviction* + Combustion*), to a total of 85% fire penetration (* ticked sources contribute to 60% of that value and don't apply for a cold version). That's an awesome value, hard to get on a cold version, and even if we get some, we have some downsides. Common sources are Frost Bomb (25%, people use it on CWDT setup - I don't like the idea to rely on taking damage to increase my damage output), Pandemonius (20% - would remove Effigon, so we need to invest on accuracy) and Heart of Ice (6% - need to invest some points to reach it).
For a cold version, we would also need to change some points on the tree, as almost all fire nodes (except for Snowforged) wouldn't be useful for us anymore. Although we have some "free" points to apply, we don't have many close nodes worth investing, and most of them need some +10 attribute nodes on the way. Most of the removed fire nodes are near the main path (Avatar of Fire, Heart of Flame, Fire Walker), requiring no additional investment, so we're trading some damage nodes for attribute nodes. Not a good deal.
Besides all I've written, I must say cold version is also viable (this is a good example). I just think they're not as good as fire version. It has higher damage (quite unachievable for cold builds), good clear speed and decent survivability (EHP comparison is questionable because we have high values of evasion and dodge).
I also must say the fire version can run with almost no mandatory items (Effigon + Tabula + 2x Cospri with the right gem setups can bring you to endgame) and it has a well-rounded overall status with low cost (specially it doesn't require the expensive cooldown recovery speed on boots). High Cyclone critical strike chance, 15 APS and high values of penetration are easy to achieve with little investment.