Spoilers
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Actually, the sphere with the 'sparklies' flying around it, that room actually, has the entrance to the 'engine room' of the planar sphere. You need to go outside anyway and kill a demon, any demon there will give you a heart. Then come back to that 'sparkly ball' and look around - there are runes on the floor. You need to use these 4 runes in the correct order to open the door to the engine room. Well, the lower levels. The 'sparkly' ball is a "guardian" of sorts, and will zap you if you use the runes in incorrect order
Leave party outside of the room, slap on fire resistance (I think it was fire heh) and go fiddle the runes. Only 4 of them, so you will find the correct combination soon enough.