Evil Wizard Smallbone, by Delia ShermanRead about another entry on the list.
12-year-old Nick has run away from his unpleasant uncle’s home into the middle of a Maine blizzard. Chance takes him to the estate of the Evil Wizard Smallbone, who takes him in (and turns him into a spider almost immediately). When he’s a boy again, Nick finds that he’s the wizard’s minion, cooking and looking after the animals. Smallbone appears to have no interest in teaching him magic, but Smallbone’s home is a bookstore (Evil Wizard Books), with just the right books Nick needs show up to awaken his own gifts of magic. And it’s a good thing the bookstore does this, because Smallbone’s enemies, led by a formidable ancient werewolf, are pressing hard against the magical boundaries of the very peculiar town that Smallbone is sworn to protect. The boundaries are weakening, the wizard isn’t getting any younger, and finally Nick must throw the weight of his own magic into the fight. It’s as imaginative and captivating as any young reader could ask for, with magical duels and encroaching enemies and spells going off in unexpected ways, and a beautifully twisty ending.