Song of purification question

ok, this might be a grammar question, but does song of purification activate the condition removal as the skill is casted( like in assassin's remedy), or when the skill is completed( ie does the effect not trigger if your interrupted/you cancel cast?)
the skill on wiki can be found here.

i think the completion, but im not too sure on that.

removes on completion

I believe it is after the skill completes casting with a successful (without interruption) activation.

btw, if you're not sure of a skill's effect, read the concise version, it usually helps

reason i was asking was because both the wording and the effect of the skill are like that of assassin's remedy, but everyone has said it only removes on completion of the skill where as sin's remedy works on activation( you don't need the attack skill to hit)