Complex sentence: Harry summons the army of spirits that sheltered at Mort's, storms the hideout through the Nevernever, and takes down the wards, allowing his allies to physically assault the hideout.
Split into simpler sentences: Harry summons the army of spirits that sheltered at Mort's and storms the hideout through the Nevernever. Harry breaks into the hideout and takes down the wards, allowing his allies to (physically) storm the hideout.