It is fun to drink a polymorph and temporary become the most powerful creature in the game. I found two tricks to make playing a minotaur easier;
1. His major weakness is health recovery. But he can wear two healing gloves. Combining with the rest bonus from standing still will allow him to heal from 0 to full health in about 10 minutes, rather than 30 minutes. He also has a chance of consuming a normal healing potion.
2. He has hard hitting attacks but a slow attack rate. Axes about every 5 seconds and headbutts about every 10. This means hit-and-run tactics work well - running away from monsters, charging in to attack, then running away again.
I killed the Grand Shaman with help from another player. I think it is possible to solo the room as a minotaur with the right technique and items, I will post a guide if I manage it.