Not sure why you wouldn't break into it if it made leveling more efficient lol >.<
Fire giants are good, shame they're not agro anymore, red spiders are apparently good, Dust Devils are also really good. (lots of crimsons here which helps a shit ton in the long run)
You can buy guthans set, maybe some super restores/prayer renewals, and charming imp then afk hellhounds
All you need to do is check in to get aggro and pot up again
I'd highly recommend Slayer. It adds variety to training, and I hardly ever have the urge to look at how fast I'm gaining XP. I can easily get 500k+ xp in a combat skill in a day of slaying...if not more. Got 99 atk very easily now almost 99 strength as well.