Is this passage worded correctly?

FYI- Szass Tam is the lich, the southern army follows the Council of Zulkirs. The southern host prepared to battle not only the warriors of High Thay, but a contingent of troops who Szass Tam had brought north from the Keep of Sorrows. When Szass Tam’s legions descended from Thralgard Keep, the Council of Zulkirs’s army immediately engaged both them and the soldiers from the Keep of Sorrows. Initially, the lich’s forces suffered many casualties and could not break the southern troops’ formations, but they started to gain the advantage after the necromancers began to magically assail the Council’s host. Szass Tam then used the power lent to him by Bane to summon a dream vestige, which began to steadily move across the battlefield and obliterate a large number of the zulkirs’ soldiers and wizards.