The latest bathroom reading is October '84's Dragon Magazine, in which the PCs can go visit Gladsheim, home of the Norse gods (and a few others apparently PCs don't want to visit like uh... Bast?), so here's a list of spells which won't work and penalized class abilities (also, you probably can't get anywhere by climbing Yggdrassil).
Old AD&D was full of stuff this offputting like class requirements and I'm having a "how did this get off the ground without being heavily house ruled?" moment.