I Easily managed at level 10 braccus rex with about 2-3 legendary items on both of my characters, lone wolves and glass cannon on hard difficulty , not died with any character, left braccus die last and only reload i had was at the deathblow for gettin better loot , on my first playthrough I had full party and was level 9 aswell , died the first attempt when he threw a fire storm and cut my team to bits in the first round heh
THE aproach to the boss is that he starts to chat, so take advantage to that , if you have full party instead of just the two like i had ( and even then) unlink them , put them in positions around the boss but as much sepparation between eachother as possible
The twin by fire joined can be killed fast by throwin ice spells at him indeed he is very dangerous as he will make your party a burn fest if left alive for too long, DO not bother givin a fire elemental on him to tank since most of the times he'll ignore the pet and go for the party members, but if you can summon an ice elemental and let that pet focus on this boss, he's as good as dead ALSO THIS boss can kill you after the fight when you're left collecting goodies... he becomes lava terrain or a bugged unextiguishable fire puddle upon death so keep the melee away (no tornado available at that point, only rain and it did not work with rain or terrain icing )
The ghoul that oozes and bounces like mad can face 1 spider and be killed by that spider in 2 turns , LAUGHABLE... just make sure you can summon the spider in the first round and as close as next to that boss to make sure teh spidey will hit instead of chase ( carefull with his bounces, wait for the animation then hit... else you risk wastin points for nothin' )
The baron will do attacks of opportunity , he's not much of a threat can be crowd controled by a few spells i think like freeze electrify etc , again he's not that much a big of a deal...
and the boss , well he's gonna go hit your mages most likely or the squishy party members, make sure you heal them or put up a fortify or become air or what not as long as you stay close to him he usually just does hits and runs around with no purpose