Power Block
A power block or "PB" refers both to a source power and the associated affliction status which disables the use of any powers, weapon styles, or stances for a short time. Much like stun, once a power block has been used on a person, they receive a temporary power block immunity to prevent a chain.
Archmage
The Archmage power "Chant of Mastery" will provide an Elf mage with between two and three minutes of immunity to power blocks.