Unexpected, and probably gonna be my last 99 since I barely play anymore.
But yeah. I got the last 2 levels from doing the Falador Invasion event. Kudos to Jagex for convincing me to (temporarily) stop putting all my xp lamps into Prayer.
This was a hell of a lot better than what we got for a Halloween event. Kinda wished they had added something else after the chest was opened, but meh.