The devil can't figure Séadna out. He hasn't beaten him. Séadna (duh!) finally realizes he's the Devil!
The Devil says it's your friends that are your real enemies! He says it wasn't Séadna that saved Máire from the spirit - it was the Devil! He sent Máire to Séadna as a couse of harm!
Everything the Devil says causes harm, Séadna sees the good in the other side of it - and gets the upper hand. A long, interesting discussion goes on. But the devil tricks him and tries to attack him.
With a sign of the cross with his jewell, a ball of fire and chains of fire pull the Devil down. Séadna suddenly fells sick and just makes it to his bed.