Right now, my usual spell rotation on mobs is:
Pyroblast (I skip this if they die too quickly)
Fireball x2
Fire Blast
(repeat until around 20% hp or less)
Scorch x4
Fire Blast
(repeat until death)
I don't use a threat meter but I never pull aggro, from any tank, with this and my damage doesn't suck. Yay for my server's tanks.
But I hear from some to not open with Pyro, for the sake of pulling threat. As I become more powerful, is a potential detriment to me? Isn't 6 seconds time enough for a tank to generate sufficient threat?