I suspect the delay between the short casting time and damage being inflicted is SE's interesting way of making Ancient Magic long cast spells without incapacitating Conjurers for 30 seconds. Instead, they treat it as a buff which when it wears off means the spell has finished casting.

Think of it this way, would you rather be stuck casting for 30 seconds unable to perform any other actions or the current system which lets you cast other spells in the delay?


Apart from that, we all know Ancient Magic damage (and all higher tier spell damage) is broken. There's no way Fire I, Fire II and Flare should ever be producing almost identical damage and not be broken. It's just a matter of when it will finally be fixed and Conjurer can be the awesome little nuker it should be.