Magids Series by Diana Wynne Jones

Rupert Venables is a Magid.It's a Magid's job to oversee what goes on in the vast Multiverse. Actually, Rupert is really only a junior Magid. But he's got a king-sized problem. Rupert's territory includes Earth and the Empire of Korfyros. When his mentor dies Rupert must find a replacement. But there are hundreds of candidates. How is he supposed to choose? And interviewing each one could take forever.Unless...What if he could round them all up in one place? Simple!

When the Merlin of Blest dies, everyone thinks it's a natural death. But Roddy and Grundo, two children traveling with the Royal Court, soon discover the truth. The Merlin's replacement and other courtiers are scheming to steal the magic of Blest for their own purposes.Roddy enlists the help of Nick, a boy from another world, and the three turn to their own impressive powers... moreWhen the Merlin of Blest dies, everyone thinks it's a natural death. But Roddy and Grundo, two children traveling with the Royal Court, soon discover the truth. The Merlin's replacement and other courtiers are scheming to steal the magic of Blest for their own purposes.Roddy enlists the help of Nick, a boy from another world, and the three turn to their own impressive powers. The dangers are great, and if Roddy, Grundo, and Nick cannot stop the conspirators, the results will be more dreadful than they could possibly imagine. less