@ LegitClaymore, Nintendoblivion - Oblivion is right in that SOME timing is needed. Ignite can be spammed up close, but the splash only goes so far; when being rushed by a dual katana user, you need to time the Ignite so they charge right into the full effect.
It looks a lot harder to use than it is. With a little practice, you'll be Igniting like a pro ^_^