"Escape to Salvation" - "Magnificent Retreat" [Campaign 4, Mission 4]

the treasure vaults of the mages are plentiful, and the treasure vaults of the dwarves are located in the first area of the map, guarded by weak Biara troops; capturing the treasure vaults automatically increases the level.

the neutral creatures are quite strong.
by this time, you should have squads that are at least as large as the Horde.

there is no point in leveling up a secondary hero.