with Blasting Workshops at Sorcery it's balanced - at the same time the Amurites can build a Cave of Ancestor and with only 3 other mana nodes plus Apprenticeship produce Adepts that instantly upgrade to mages, with spell staffs and the potential to have more spells. Of course they are not Strength 6 like the Wood Golems (both cost 90) but then wood golems don't have promotions. Iron Golems come much later in the game (or at least need a completely different research path). Sure, to get Iron Golems with Fireballs is nice, but to get there takes quite a bit of skill. If your not convinced I would propose to make Blasting Shops a (rebuildable) National wonder, so it would decrease the ability to produce them. On the other hand Cave of Ancestor is no National Wonder and I really would not recommend to make it one.