The boss is Tomithy. You can probably kill him as soon as you reveal him

Default gods are Earthmother, Jehora Jeheyu, and Mystera Annur. MA is hidden behind a level 9 Dragonspawn, so you'll need wallbreaking or WEYTWUT to access her before you've killed the boss. BURNDAYRAZ is right next to the entrance, don't waste a prep on the magnet. Other glyphs I found were BYSSEPS, BLUDTUPOWA, and CYDSTEPP. I did not reveal the last glyph before finishing.