You know what Sabbath almost always did right? Keyboards.

The Dio and Martin years have such good synth in that music and I think it's how tasteful they were in using it. I can't think of a song where the keys are too loud or distracting from the music. It's mostly for vibe/aura and it adds so much. Cross of Thorns and Devil And Daughter come to mind immediately. Nicholls does such a great job of making they synth a rhythm instrument and a lot of the Martin stuff in particular would be worse without him.