But murder = tons of exp.
Does he eat the Yarrow flower? Or does it remains in his inventory. Because if he eats it, rip recyclable Elixir for great gold.
You get XP600 for giving the ring to his mum. She then goes to the beach, you go and talk to them and you get the key for the entrance to Orvids Chambers.
If you want you can then kill the happily reunited pair and get XP1000 for Migo and XP600ish for his mum and get the Yarrow flower and the ring back from their corpses. Or you can pickpocket them. Many options...
