Vanish vs certain spells

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?

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.