Apparently, Swedish death metal band Entombed will support Iron Maiden here in
Scandinavia at least. Originally, Halford was up for the part.

It's no about needing anyone to maximise their arena pulling potential - or having cred. The reasons for having support bands mainly are financial/logistical ones, plus it's more value for money for the concert goers to see more than one band.

Personally I like it if the headliners and support bands are somewhat similar in style.

I just love it when both the headliner and support bands are major bands. Mr. Big
supporting Aerosmith springs to mind. Amazing stuff...

Stigma