In any Glorantha game eventually you are going to eventually get into the strange world of heroquests. These are one of the coolest ideas in Greg Stafford's creation – by entering the world of myth and legend and mucking about with the contents thereof you can gain great power and magic items or even change the 'real' game world.
An example is the Yelmalio Hill of Gold quest. Yelmalio is a sun god who can't use fire powers as during the mythic godtime he was defeated by first Orlanth and then Zorak Zoran. A Yelmalio cultist can do the quest and if he beats Zorak Zoran he regains the fire magic his god lost and which he is otherwise barred from using.
Trouble is heroquests are a but dull in actual play. Players start out knowing the story and they trog from one encounter to the next doing whatever it was their deity did in a pretty linear fashion, with limited options for player agency.
But the otherworld is supposed to be a vast landscape of clashing possibilities, and you can go 'off-piste' and ignore the established traditions and make your own myth for fun and profit. The historical conflict of the Gbaji Wars, the clash of the EWF and Godlearner Empires and the unfolding Hero Wars are fought out on the otherworld as much as on 'mundane' Glorantha, guerilla heroquesters mangling myths to gain allies and weaken enemies.
You could set them up as dungeons or wildernesses, but that misses the point, these kinds of adventures are supposed to be different, wandering through linked events as much as locations. So I am going to be using Chris Kutalik's pointcrawl idea, detailed on his Hill Cantons blog, mapping the otherworld not in terms of actual terrain, but key locations and the ways you get between them, more like an abstract railway or metro map, and of course taking whatever liberties with time and space and simultaneity you like along the way.
Here is a heroquest I wrote for my ongoing Griffin Mountain Runequest game, though when we played it the PCs wimped out at stage 1. I'm keeping the terminology of MRQII's section on heroquests from the Cults of Glorantha book, but only as guidelines and certainly trying to make it more fun than a series of skill rolls.