Mana cost is spent throughout the skill instead of on use; cancelling the skill or getting stunned will not consume mana. Most skills can be cancelled, with dodge roll forcibly cancelling most skills.
Spirit: A new resource called Spirit is added in addition to Life and Mana. Spirit is used to reserve skills with persistent effects like buffs and auras, upkeep permanent minions, and enable trigger meta gems. Spirit can be increased through story boss rewards, modifiers, and sceptres.