I'm playing a cold caster atm and it's been a breeze all the way through vet. Biggest downside is that it's pretty damn boring.
The lack of a cold spell specific spammable spell hurts it. You can supplement Trozan with component spells, but they are kinda boring and weak after Normal/Vet. Fire has the same issue although Grenado and Canister Bomb help a lot more than Trozan does. You people building Cold casters should upgrade yourself to a fun style and roll as a Lightning Wizard. Now there is a fun build.
Magic missile works well enough. Just hit lvl 50, gonna mop up the last few remaining areas and then head over to elite, maybe respec later.
It's functional but lacking if you want to make a themed elemental caster. Overall it's an incredibly mediocre spell that falls short vs DEE or Fire Strike with Brimstone.
PRM is fine, dude kills ultimate fabius in same time as brimstone DW pistols:
http://www.grimdawn.com/forums/showthread.php?t=34478
Guy is decked out in Legendary items. It literally does not matter what kind of shit build he'd run, it'd work no matter what with that gear. His damage isn't particularly impressive either. My DEE crits for about the same amount except it also has a DoT critting for 20k on the side.
DEE would not leverage Arcane Bomb and Argivix like PRM. You can get a lot of Aether damage on PRM and buff a bunch of aether and -res the aether. DEE can be leveraged just fine and obviously this guys equipment and devotions are an important part of the build. But just comparing two skills is not insightful towards its performance and you can't assume there are equipment analogs for all build types.
Although I suppose if your DEE DPS kills Fabius in 20sec when you are all legendaried out that would be a solid number showing its better. The only one i have seen that is faster than 30sec is a melee DW with really high attack speed one.
And you can supplement DEE's damage with Vulnerability and Acid Spray. Both debuffs stack btw. And it is possible to compare the two skills since they are essentially the same except one of them has weaker DPS and AoE (PRM).
I'm kinda interested in Arcane Bomb providing an Aether debuff now though. I see that Eldritch Fire provides one for Chaos as well. I might make my Chaos Warrior now since the lack of Chaos debuff was holding back that specific type of damage.
Well chaos and aether still have some res problems since cultists and aetherial tend to high res to the one they have affinity and you are basically stuck with Witchblade(chaos/fire)/AB(aether/lightning) devotion + acid spary(universal). Vulnerability will do elemental/vit/bleed/phys/poison&acid but none for aether/chaos.
Really the fire or lightning can stack a good bit more, Occulist/demo being the most because of thermite mine (which is something like -50% fire/lightning and like 33% chaos give or take). Since hellfire on thermite also debuffs chaos I think chaos may be better than aether. However Arcane bomb is really damaging and maybe better than witchblade devotion for the actual damage part, Ithink it also does a higher debuff at -33%. So in the end you can maybe get mostly similar res debuff (maybe 10 less?) for less investment.
Poison of course has the NB aura which can also be pretty great but Acid spray is not specific to poison so there is no second devotion with a -% to stack on it and Mark of Dreeg won't stack with it either.
Brimstone builds seem really tight and leveraging a pyromancer to get max fire and chaos resistance is kind of hard with only 85 levels. Elementalist Primal strike or savagery(without procs) + various lighting only -res is strangely somewhat easier to fit and still works very well with Arcane bomb as the lightning and aether parts are roughly equal.
Arcane bomb is really nasty paired with Grasping vines. It can clear groups of normal in Elite all by itself with a lightning focus and procs almost instantly. Also it has -OA so it helps some defensively.
Anyway I think a chaos route is pretty viable but you probably really want Demo for the mines. On the other hand I while I have not extensively test witchblade devotion (I know its pretty good) I have a strong suspicion Arcane Bomb is overall better by a good margin. So perhaps that makes up for Chaos having the extra -res possibility from hellfire mines. Eldritch fire though has no listed recharge and spreads while AB has recharge but hit in a 5 meter AOE. They are both very nice damage.
I believe it is actually lightning that can be debuffed the most (ignoring vitality/bleed) because thermite is such a large debuff so its either fire or lightning and arcane bombs is I think about 8% more -%res. Fairly small difference there though. Chaos comes in fairly far behind at like 50 less due to hellfire being less than first part of thermite and nothing on Vulnerability and maybr 40 less than Fire. But all in all still a pretty hefty amount of minus res at -33+-20+-25 for about -80.
Also chaos gets no benefit from the viper 20% off elemtnal res. but fire and lightning will (personally this is meh to me I can't even fit viper into my 2H lightning build due to using kraken, but for a non two hander its something to consider since they give same color points).