Mana Pools are special locations where Mana is generated. You can claim a Mana Pool by moving onto it and paying a Valour cost to claim it. Once claimed, a Mana Pool will pay you Mana throughout the day.
If a zombie reaches a Mana Pool and blights it, a zombie boss will be created. Zombie bosses have unique powers and attributes that affect the whole map. When a boss emerges, it is likely that all players will have to stop what they're doing and cooperate until it is defeated.