@Shadow Dragon no they use the spirits to accomplish their task they actually do not know/use magic , when Brom is explaining to Eragon this is what he says " No sorcerers and witches do not use magic, Sorcerers use spirits for their bidding , and witches use potions"
@Sharidi37495 he isn't in the island lol if you read his posts he never went to the island he's been wandering alëgasia and he scared a town and then Siamyo suddenly appeared and started talking to him