anonlineuser
Skeletron
Up there, at the start of the summoning section.Just make the skull require Hallowed Bars instead.
As for fixing the summoning, I'd say remove the mech summoners entirely and make it cost: 15-20 chloro, 10 each of souls of night and souls of light, 20 bones, and maybe a couple lenses. I'm opposed to the 'replace mechanical eyes with suspicious looking eyes' since then it would cost 12 lenses, which is hours of farming.