RDM - What am I doing wrong if anything?

[Ferrasper]

Why wouldn't you start to hardcast thunder 5s before the pull? Also being a caster doesn't mean you have to be at Wal-Mart casting spells while your party is relatively stacked for healing and buffs.

Because the cast takes too long that's why. It would be easier to start if off with Jolt 2 or fleche. Coming from a caster main with all three at 70. The closer you are grouped with others. The more likely aoe are to target you which is why you stay mid-range to far away, so yes, standing a little distance away from the bosses close aoes and such is a good thing. You can still still be close enough for buffs and such mid-range and not be in the fray like you are melee. You are called ranged for a reason.

I am not talking about the corps-a-corpse because obviously you have to get in close for the combo. You always have to plan that one out just in case it goes into a phase or something.