Here's a hastily written guide to my pull strategy and my build. Comments are greatly appreciated. I know it could also use some organization, so I'll try to put some time into that once I get feedback.
my standard pull strategy (most I've seeen scattered around on the forums, but some is purely from my experience)
For large groups of weak mobs (couple levels below me), I inferno of amher them to pull and then waves of flame them. This is faster than using FoG.
For harder mobs, the best strategy would probably be inferno pull and then FoG each target down individually. Using inferno/waves of flame the whole time will leave all the mobs alive for too long and once PoT breaks, you better have at least one or two mobs killed. If you're facing more than 2-3 mobs, you probably want to inferno whenever it's on cooldown and FoG the rest of the time because the total damage of each inferno will be useful. From my experience, using waves of flame in close battles doesn't seem worth it since the dps is pretty low, at least given that I have not taken any feats to improve it.
The more mobs you pull, the more effective the initial aoe will be of course. Using chains can help as well. Chain one mob and then have the rest come toward you, ignoring the chained mob until it expires. If you have a caster and melee, you might also want to chains the melee and FoG the caster to maximize FoG aoe potential while keeping the melee mob at bay.
Remember that mobs can stil attack whiled chained, but can't turn around. So if you're in a critical situation, chain a ranged mob and run behind it.
I have not gotten to the level where I can put points into combustion, so hellfire stream does roughly the same dps as FoG. However hellfire stream and shock are still very useful because they let you kill mobs that are at low health faster than just FoG. This can save you time when facing 1-2 mobs and can save your life when facing more. When facing 3-4 mobs, getting them down one by one is critical since it reduces the damage you take. However, be careful and only use them when you know you can kill a mob. If the mob is alive after both are cast, you'll have to use FoG to finish it (since hellfire stream and shock both have long cooldowns) and you've just wasted at least 1 second and mana.
My recommended conflag build and the one I plan to take is
http://feats.goonheim.com/demonologi...a5b5g5h1i3o2p3.
It's purely meant for pve leveling and focuses heavily on FoG.
First I'll cover my general tree choices.
I decided to go with spiritual armament over spiritual aegis since the vast majority of pve mobs deal some sort of physical damage. I could have taken aegis as well, but felt it was probably not worth it for pve. I'm guessing it would be better in pvp.
Crimson shield provides almost no benefit and archmage is useless as well. For those who don't know, 5 points in archmage means having either the fire or lightning buff on means you effectively have both on. Since the only lightning spells I use are chains and shock, and not all that often, this feat seems like a complete waste. It might be useful for a build that put points into both havoc and conflag, but I don't even think that's viable at this point.
The mystical attunement buff doesn't seem all that high for the regular FoG damage, but for aoe spells and for the FoG dot, I think it will help a lot. Quickened iron seems like a critical feat since my demo seems to do fairly well against a large group for the first several seconds, but drops like a stone when PoT breaks. The damage return from mirrored iron doesn't really seem worth it, but I put 1 point in anyway since it was left over. I picked unleashed power primarily to increase the aoe range of FoG, since its aoe damage is quite significant. Elrik and I left out the two chants since they seem to barely scale.
For the conflag tree, I mostly went with spells that boosted my FoG or fire damage. I thought about consuming flames, but left it out because I was told the mana regen is not too signficant. I also left out devouring flames since the dot isn't usually what kills mobs, so it doesn't proc all that often. I upgraded inferno of amher since I use that fairly often against large mobs and went for gate of hell and let them burn simply because they are both really good. While gate of hell may not be as useful for pve as for pvp, I'll be close to 80 when I get it anyway, so I may as well have a nice stun, esp. for pvp.
I am lvl 32 right now and I've been going down the conflag tree. I can say that upgrading lingering flames is quite useful as it does a fair bit of damage and is really handy when I go oom and the enemy has <10% health. After finishing the first 4 tiers of conflag, I think I'll switch over to general for some better defense. Right now, I just need to finish unholy war and demonic hate. The rest of my feat choices are solely based on what I read on this forum and experience with somewhat similar feats in other mmos (mostly some of the general feats).