Interrupting

I was just wondering how "easy" it is to interrupt spells since everyone seems to take them into their builds... On paper the builds all look nice, ow yea, first we do power leak... then we power spike... What is the minimum casting time you need, i know it is variable from person to person, but what is the minimum you need ? 2 secs must be reasonable... Maybe 1 sec? Lot's of people making interrupting builds, but that allready requires lot's of skill slots dedicated to interrupting... Do "interrupters" need Arcane Conundrum or migraine to be potent?

Actually, interrupting is not extremely difficult, you just need to be fast. Essentially, when they start casting and you have them targetted, the spell that they are casting appears near their name. This is the time, to interrupt. Of course, Mesmers can cast even faster, so get a small amount of leeway. The interrupt spells are usually 1 second cast time, so they fire pretty fast, but you still need to be "quick on the draw" otherwise you will just use energy.
Arcane Connundrum is nice, but not essential

Actually, I have a Signet that interupts spells that are being cast, while active it actually hurts them and gives me life.