Shield Block is a warrior ability learned at level 18 for those with the Protection specialization. It is a defensive ability that allows warriors to block all melee attacks for a short period of time, provided they are using a shield.
Patch 6.0.2 (14-October-2014): Shield Block now regenerates a new charge every 12 seconds (up from every 9 seconds).
/Patch 3.0.2 (14-Oct-2008): Shield Block now increases chance to block and amount blocked by 100% for 10 seconds. Cooldown increased to 60 seconds, rage cost reduced.