The Overarching Plot

The main plot of the campaign is The Return of The Magician of Old, a crazy strong wizard who reset mortal civilization, nearly killed a god, and brought an 8,000 year age of ruin upon the mortal world. He is trying to resurect himself, and the campaign should end with him either being defeated, or the resurection being stopped. The parts of his soul has possessed different wizards around the world. Most of those are working towards his resurection, but one is working against it. 
How active the main plot is will differ. To begin with the A plot is heavily involved, as the B plot is the situation in the County of Katrach, where sorcerer lord Malakesh, who is possesed by The Magician of Old rules. Here, there are many factions at play, and some of them wish to overthrow the sorcerer. If the players choose a side, this will be the first real arch of the campaign, to (most likely) defeat the Sorcerer Malakesh. That should take them to level 5 I think. After that, I want the second arch to be less involved with the A plot, and instead focus on their personal goals more so. I want to bring them in towards central Rynkowskian land more, where we can interact in more political enviorments, with organisation and factions that plot against one another. Here there should also be oppertunity for players to establish themselves politically in the land. 
Then for the third arch, I want them to interact with something that they dont realise has a connection to arch 1 and the larger A plot, but at the end they start to see some loose connection. Then again, personal goals. By the end of arch 3 they should be hitting level 8-10 probably, which means they are now important people in the land, who can have serious levels of influence. It's at this point I imagine plot-points like retaking Dumiria can start to become relevant. 
Arch 4 should be mostly about personal stuff, like retaking Dumiria, Ren really establishing himself, and if it's not done already certainly freeing Nozak's village. There might be a part where we investigate the murder of Bam's parents, finding out that has some ties to the main plot, I mean its always sick when the bad guys killed your parents, especially if you find out about it late, and realise this motherfucker has always been against you. I also want the end of Arch 4 to be when the possessed ones kickstart a war, some invading armies should appear, giving our players a chance to utilize their political connections to fight back. 
Then tying things into arch 5 I want there to be some serious revelations about how things tie in to one another. Also, the beginings of war in the last arch should turn into all out conflict now, with hordes of enemies swarming into the land that our players have come to care for, beloved npc's dying left, right, and center. This should be when they uncover the location of the last crypt, and try to get there before the leader of the possessed do. Ultimately, if they fail, arch 6 will be the ending where they have to face of against a fully resurected Magician of Old, and have to gather powerful allies to face of against him. Alternatively if they get to it first then the finale could be them being fooled into giving it up to the possessed one who initially resisted the possession, but has now lost control, and as such The Magician of Old is still resurected.
As mentioned arch 6 is what I want to be the epic showdown, mega battle. Maybe the war rests on one battle, and in the middle of it our players have their showdown with The Magician of Old, while his minions and generals are distracted by the allies our players have gathered at this point