If you don't follow the whole JUPP principal of having a decoy for HOF mode, what are your strategies? Does the game break down to a whole lot of summons and mass destruction spells? Is there another way to do this mode?

TIA

Use enchantments. Hold Person and Symbol of Hopelessness "freeze" enemies for your dining pleasure. A typical tank character designed for normal mode can still be devastatingly effective with the help of these spells. Spells like Charm and Dominate lets you let your enemies hack down each others' HP before you kill them.

I'd also add spelltraps as another option. It's true that Web etc aren't as good with heightened enemy saves, but they are good enough when combined with save-reducers and summons/charms at the edge to keep enemies within the kill area. Grease, Spike Growth, Acid Fog, and Entangle (IIRC) all reduce movement rates with no saving throw, or even if a save is made.

You will find that you want to use any and all strategies, depending on the circumstances. A spelltrap is the right option to fight an attacking horde, summons are good for running battles and two-front battles, and enchantments are ideal for ambushes.

Cool, thanks a lot!