Blocking is a Warrior's ability to cancel all damage that would have been done to the warrior.
The warrior can block continuously by holding their secondary action button [right mouse click by default]. Berserkers must use Shields to block, while Guardians can block with Sheilds, Great Weapons, or while Dual Wielding. While blocking, the warrior's Blocking Power Bar will decrease. A successful block cannot occur when the Blocking Power Bar is fully depleted.
When the warrior releases his block, he performs a powerful attack that damages and possibly stuns all enemies around him. The power of the attack depends on the warrior's MP bar and how long he blocked. Blocking for a short time will cost a little MP and will deal a little damage, while blocking for a long time will cost a lot of MP and deal a lot of damage.
If the warrior successfully blocks an attack, his Blocking Power Bar will partially deplete, his MP bar will fill up, and he can perform a maximum power block attack.
Blocking gives you a chance of knocking out the enemy, depending on that skill level. It will do damage most time, but the most attack point at a small level is very slim. Blocking is available for both berserker and guardian, but is mostly for guardians.