I suggest you play it through without cheating. You've made it to the end of the game, and you are within touching distance of the end.
It would be a big shame to lose your 'slow-heavy' roleplaying at this stage of the game. Just persevere and try different things.
Project Image > Summons > Wish to regain spells > Boost Spells (Haste/Bless/Prot Evil 10').
You can easily (!) get 100+ skeleton warriors, which I think should be enough even for this fight. If your computer is still able to do anything
