BLM - what rotiation for highest damage (low level).

I've started levlling a BLM. Running the lower dungeons I'll usually throw a Sleep, or Thunder + Sleep on a couple enemies then start just trying to do as much damage as possible on the tanks target.

With the attack Skills available in, say, Sastasha (Fire I, Blizzard I, Thunder I, Scathe), what rotation would you recommend? Currently I start out with:

Fire I until MP gets really low
Transpose
Thunder I (if not up already (not usually at this stage))

What I then can't decide is whether to:

a. Use Blizzard till the transpose is available again
b. Just Start casting fire (first will be weak / cancel Umbral Ice, second will be mediocre with neither Astral fire or Umbral ice, third and beyond will be Strong with Astral Fire)
c. Use scathe until the MP fills and the Umbral Ice wears off, then cast fire (from no buff) continued by fire with Astral Fire buff

Please give reasons of figures with your answers if possible.

I don't have a parser or know how to set that up, so it's tricky to be able to work out which rotation is best.

First off, always start with thunder on your main target (tank's target). That way you're still doing damage while casting other stuff. Also, while BLM is good for crown control (sleep) it is very rarely--not never, just rarely--worth it in low level content.

My advice: thunder -> fire -> no mp -> trans -> blizz or scathe till close to full mp -> trans -> fire. Weave in thunder at any point when it's about to drop.

I'd recommend using thunder on the lowest priority targets first, to ensure they have a chance to last their full duration.

Also I'd start with blizzard first, then transpose, then fire1 til you can't cast it any more. Blizzard 1 and fire 1 have the same potency when not in astral fire or umbral ice. Opening with blizzard allows you to maintain full mp and jump right into one stack of astral fire which is a 40% buff to fire spells, this allows you a larger mp pool for the entire astral phase.

Only cast thunder when in the umbral phase, just make sure you cast atleast one blizzard spell before umbral ice falls off, since the buff duration is shorter than the recast on transpose.

Also don't cast thunder if there is no chance the mob will live for the full duration.

Thanks, both of you :) So some slight differences to experiment with, but I see you both have opted for waiting for the transpose cooldown when switching either way (astral / umbral).

try this: Fire until you have enough to use 1 scathe and 1 fire.
scathe, transpose.
and then repeat fire again.