WotLK Vanish vs certain spells

[deathpala]

Hello,

Ive been searching but i couldnt find what i was looking for regarding rogue vanish ability.Maybe you guys could answer it for me.
How come when rogue uses vanish his immune to spells , to be specific "blood boil" DK spell.I can see rogue but i cannot hit him with it while vanish "improved stealth" is still up?
Also hunters "piercing shots" debuff wich is bleed gets removed with vanish? Or it is magical ability?

[fdbsfhe4rfar]

it's not vanish, it's cloak of shadows. the rogues use it prior to vanish to resist 90% of the spells you throw at them if they vanish so you can't find them or reveal them.