1. Training Grounds N.W. of Ardougne (just inside gate) 2k xp lamp
2. Mountain Camp (just a bit north of Relleka slayer Fairy Ring) just outside shortcuts on the big map 5k xp lamp
3. Shilo Village (North half of village, need to buy a dormitory ticket to visit him) 5k xp lamp
4. Port Phantasmas (Just inside the bar) 10K xp lamp
5. Polypore Dungeon (all the way downstairs, just by the last vine down) 10k lamp
6. Dorgeshuun Mines (just outside Oldak's house) 10K lamp
He leveled to 100 from the end of quest, not sure if there are more locations (if there are I expect that you must meet combat level requirements to access them)
Please update if you have more info or if any of my info is incorrect

Another quick fix here, you MUST use your lamp before he appears at the next location (thanks Satrianisaxe)