I'm planning to play through this adventure soon with a party of 4 starting HOW characters; Wizard, Human Fighter, Elven Archer and Dwarf warrior (as per the character sheet at the back of the rulebook) in next few days.
For anyone who's played through OHM, would Invisibilty or Magic Sight be too powerful for this beginning adventure? No spoilers please!!!
The only tweaks, I'll make to the rules are limiting starting spell levels to IQ12 (or possibly less), a couple of spell tweaks and a few changes to the weapons table
definitely wouldn't drop down to 3 characters. using LAW rules, OHM is very challenging to me with fresh characters. i can't imagine how Mage Sight would be useful. Invisibility will be good for whoever is invisible but bad for whoever is not.