Mana

Mana (also known as MP, which is short for mana points) represents the magic power of a unit. It is used as a cost for the majority of active and even some passive abilities. Every hero has a base mana pool of MP, while most non-hero units only have a set mana pool if they have abilities which require mana, with a few exceptions. These values cannot be altered. This means that a hero's maximum mana cannot drop below MP.