20 str 13 dex 8 con 11 int 8 wis 10 cha First lvl the barb to 4 then get 1 into sorc after that lore should be 8 so start placing 10 lvls into RDD the RDD bonus should buff stats into
28 str 13 dex 10 con 13 int 8 wis 12 cha
but your own bonus stats on str should be adding upto
31 str
after 10 levels into RDD add 4 more into the sorc so you may pick up truestrike, bullstrength, and flame weapon trust me its REALLY helpful
so the lvls should be 4barb 5sorc and 10RDD so far starting now add every single level into barb and concentrate on grabbing
and the gained stat bonus should be distrubeted with 4 into constitution and the rest all into strenght so your rage should last a good 5 rounds enough for a barbarian to deal a big dent into any foe and whirlwind while raging is a very powerful attack to everyon around you but it dents the time left in your rage so deciding the time to use it is important. THATS one big build if you ask me lol but hey it works
and if trying it with any other weapon just modify the feats to them not so hard is it?