Blackout

Blackout was a priest talent that has a chance to stun an opponent for 3 seconds. Blackout triggered from damage spells from the Shadow tree, but not from Shadow spells in the Discipline tree (such as Mana Burn or Feedback). It did not trigger off spell ticks (such as each tick of Shadow Word: Pain), only at the initial hit of the spell. The chance to trigger depended on the number of talent points invested, increasing by 2% for each point, up to a maximum chance of 10%. This talent was usually taken by PvP Shadow Priests in lieu of Spirit Tap.