Dragon in Observation

In the next adventure of the two young descendants of Merlin, The Dragon Lord, Beelzebub, learns about the magical Celtic ring. This ring which has been possessed by the Shipton coven for 1400 years, confers ownership of Excalibur. 

The two children time travel to save their Aunty who is the coven's Keeper of the Ring. First, the children have to battle a necromancer in an alternate world then a badly cast spell sends them to another world and more necromancers.

Life is never simple and the cousins have to survive dangers in two worlds, but John does pick up the ability to create spells and increases his powers.