Blood Rage is an ability of the Squire that is unlocked at level 20. Under its effect, the Squire's damage and speed is greatly increased.
Blood Rage is a skill best used against bosses. Because of its mana cost, it is advised to use this only against bosses, in dire situations, and when all of the defenses are built and fully upgraded. Blood Rage is particularly effective in the Ogre Crush and Monster Fest challenges.
Leveling and costs
The mana cost each second is 30 during the first 8 seconds, but after that becomes a quadratic sequence where the new cost each second is approximately the previous value plus the current number of seconds since Blood Rage was activated.
Adding more points to the skill increases the damage dealt and reduces the amount of mana needed after the start mana is used. The starting mana amount is not reduced.