Bizarre, haunting, beautiful. It's a different way of singing. I've never heard anything like this before. I feel like I've discovered a new color not previously made available.
Iron Maiden, have been to one of their concerts many years ago.
Tho the newer albums (last one from 2010) are good I often find myself listening to their old songs.
And another one from Insomnium (again could be that need to turn down sound a bit)