WoWDB

Discipline, Holy:

When you deal critical periodic damage with your Shadow Word: Pain, you have a 100% chance to summon a shadow version of yourself which will slowly move towards a target which is afflicted by your Shadow Word: Pain. Once reaching the target, it will instantly deal [ 393 + 37.5% of Shadow Spell Power ] Shadow damage.

You can have up to 3 Shadowy Apparitions active at a time.

Shadow:

When you deal critical periodic damage with your Shadow Word: Pain, you have a 100% chance to summon a shadow version of yourself which will slowly move towards a target which is afflicted by your Shadow Word: Pain. Once reaching the target, it will instantly deal [ 394 + 45% of Shadow Spell Power ] Shadow damage.

You can have up to 3 Shadowy Apparitions active at a time.