Seems like you're way too slow then... try using "Haste" in the begining instead of Aura and if you're still to slow... then just wait with 1 character on standby until Meteor is cast and then heal your party as soon as possible. You MUST be completely healed before Meteor. Remember: Being fast is one of the keys to an easy victory. What's your characters speed stats? Omega have 62 in speed, so try to be faster than that. Also, use Haste in the begining.