How to defeat Lord Reonall on crack Options

[Patrick_hindman]

Hey guys its been a long time since i've played because uni work got the better of me. I've started a new party multi-class fighter/mage, riskbreaker, beserker, necro, priest of lathander, and cernd(auramaster). The party i've got is pretty high level with both fighters and necro at level 13(verging on 14), and i've taken care of most of the quests in chapter 2-3 but i cant complete the fighters stronghold because i cant kill lord reonall and his army, lord reonall is practically invincible, his physical resistance to all forms of damage is extremelly high(i can only get at max 5 damage with any weapon type i'm weilding) and when he has hardiness hes physically immune, he's apparently immune to all spells 5th level and lower so breach doesn't work, has got alot of hitpoints and high regeneration. Most of his army can be disabled through enchantment spells but even they are tough with each of reonalls guards each of them able to use hardiness(though are vulnerable to magic at least), golems and a high level mage to boot.
Really this battle is crazier than the shade lord battle, need some advice or do i need a higher level party to beat him.

[Sikret]

The battle with Lord Roenall triggers many weeks after gaining the stronghold. I wonder what you were doing during this long period of time. You could go to underdark and return and do many other quests. The party levels are normally far higher than 13 or 14 when this battle triggers.