Door Into Faerie

In the final book of The Shards of Excalibur series, Ariane, Wally and Rex Major (Merlin in disguise) are converging on the final piece of the sword Excalibur: the hilt. When Wally uncovers its location, Ariane and Wally must figure out how to reforge the magical sword in order to defeat Merlin forever. With the pieces reunited, the door into Faerie opens, and what emerges from it may destroy everything Wally and Ariane have fought to save.