Ok i know reading is overrated got to answer the OP post now Kappa.
For LC0 a good idea is to put all your points into energy and invest 2 points into Lorenado . For the Barbie it should be 2 points Earthquake , 2 points Lion Stance all Strength .
You can play until lvl 18-20 as a caster then gamble a warp blade and respec there . Good runewords are Shark weapon , El rune into armor , Eth into Belt rest make jewelwords .
Oh yea i am dumb i forgot to say make a bone shield gemword lategame with MF jewels + Rainbow stone to get super MF shield lol.
By the end of Act 1 before attempting Smith get a banded plate or ceremonial armor and make a runeword out of it . By level 30-35 you can switch to T2 gear same runewords+2 socket jewelwords and then stick mystic orbs into them and they will carry you trough Hatred unless you do /P8 .
Notable mentions :
Act 1 mercenaries we love are priestess because of Spore shot + Shockwave +Sol bow raping enemies since alpha . later you can give her a +Nas runeword to freeze stuff
Act 3 mercenaries are very good eveh without gear later just give them + skills and some crafts of their suitable element
Act 5 barbarians use Gift of the Wild . mark of the wild item bonuses such as robe of leaves +70% spelldamage apply to it so if you play a caster this guy is pretty useful