Depends on your definition of hard, I wouldn't call it hard as much as fiddly, especially if you're using moonwell chalice in your main gear set. There are some gimmicks that'll boost your dps significantly if you have the right conditions, namely access to a second set of gear that you can stack mastery in, moonwell chalice, and a raid group that does proper countdowns pre-pull. I guess as it's 385 ilevel you've probably not raided on it enough to have the extra gear to make a complete set, but for example what I do is >30 seconds before the pull I switch to my mastery stacked gear set (moonwell chalice, all gear switched to higher mastery pieces where possible with full mastery gems - excluding pieces where switching gear triggers an icd). This gear set has about 3.4k mastery, 5.1k with chalice active. During the countdown before the pull I pop chalice, use a macro to equip
Fire of the Deep (due to the behaviour described in
this post and pop meta (with 5.6k mastery), pre-pot and switch to my regular gear set, and then combat starts. I lose a second or two of meta depending on how safe I want to play it (getting stuck in a gear set with multiple strength pieces fully gemmed with mastery because you tried to cut it too fine is quite embarassing), but first meta with 5k mastery rather than 2k makes it worth it.
Doomguard's still a very powerful cooldown for you so unless a fight dictates using it at some particular point, use it as soon as you've got most of your procs up. It does scale with haste from gear (but not external haste buffs, heroism or 5% raid buff) so if you're using a haste proc trinket make sure you time it with that (this is the reason why insignia of the corrupted mind knocks will of unbinding off the bis list for demo). If you've got 4p t13 time it with that as well of course.
Try to make sure to get extra meta-buffed doom ticks where possible. So with your first bane of doom, don't refresh it, let it get all its ticks out and put it back up as soon as it's fallen off. If you refresh it just before the fourth tick, you won't lose a tick, but the fourth tick will be calculated based on your buffs when you refreshed it, so no meta, no demon soul, etc. Similarly if you've got a non-meta doom up and meta comes back up, refresh doom before it ticks again.
Incinerate spec is generally the way forward, though I still actually take bane a lot of the time due to the number of multi-dot fights and I'm too lazy to respec on a fight to fight basis during farm.
My pull sequence, after the mastery gear swapping described above, is: incinerate to get 5% spell crit debuff up asap (pre-casting in the last second of countdown - shadowbolt would be slightly more optimal despite it's longer cast time if you're not doing a pre-combat meta, might even be with pre-combat meta but I'm used to this) -> elements (skip these steps if your raid has them covered by others) -> immolate -> soulburn + demon soul + racial -> hand of guldan (pet crit debuff asap) -> bane of doom + felstorm -> corruption -> immo aura -> doomguard -> shadowflame -> incinerate (felstorm should end here) -> summon felpup -> continue with regular priority. Not sure it's 100% optimal but it's so ingrained in muscle memory by now that I'd need to see a significantly superior starting order to bother changing anything. If trinket doesn't proc I'll delay certain things though.