Nebulous
Legend
Sounds good. So how does the party prevent this? Or is it impossible to stop? Is the only option to confront and destroy the prince when it enters the world?
The reason I ask is one way of stopping it is setting the requirement that the summoning of a prince requires three of the nodes to be closed. One prophet + one weapon + one node (all of the same element) and all other nodes closed = a prince being able to enter the world. The problem there is that if you go with opposite weapons (or prophets) close nodes, it becomes impossible for that situation to arise. So now I'm rethinking it...(but I don't probably not, see below)
As for the Elder Eye...I think I am going to go with some of the powerful cultists (not prophets) are actually followers of the Eye and working to bring about the end of the world. They are there to make sure that the above situation occurs and will manipulate prophets, PCs or whoever to accomplish that.
(For my game) the Elder Eye itself does not need to be summoned. It _is_ the fane...or the fane is part of Tharizdun...the gods didn't imprison Tharizdun, they shattered him and parts of him scattered throughout the multiverse. Most just are floating harmlessly in the voids between worlds but sometimes one lands on a world (like the Loc nar from the Heavy Metal movie). His will lives on and occasionally he is able to will one of his shards to grow and influence the creation of cults and elemental nodes. It is limited in that it can only create all four at the same time but he needs them to grow in power then destroy each other so that only one survives to summon it's prince. One prince in a world will create an imbalance that will quickly destabilize that world and destroy it, freeing that shard of Tharizdun back into the void so it can land on another world and repeat...More than one prince would just result in them destroying each other.
So back to my question...maybe it is not possible to prevent it. Once there is only one cult that has all three components, that cult can summon it's prince. Either the heroes will rush this process along or the cults will eventually go to war with themselves and make it happen under the subtle guidance of the Elder Eye cultists. So the last two prophets go to their node hoping the party will follow the other remaining prophet and unknowingly sacrifice him/her. When confronted they will fight because they want their prince to enter the world so they hope to drive the party back (of course they expect to be well rewarded by their prince for summoning it...but it will just eat them).
Closing the node while the corresponding prince is in the prime material plane will banish that prince. So a clever party will try to get past the prince with the right weapon and close the node rather than fight it.
As far as level progression goes...I'm letting my group level to 8th (three sessions at 7th and killing off two minor villains is enough, I think). Once they kill a prophet, that will get them to 9th. Second prophet 10th. Third prophet 11th. So they well be 11th to fight the prince...will that be enough? Deadly encounter for four 11th level characters is 14,400 XP. 18,000 for an elemental prince should be all right if they are not too drained from earlier fights...
I guess we'll see.
Dang. I LOVE that idea of the Fane being a shard of Tharizdun. Only the Cult of the Eye would know that. Yeah, I think this will work, good ideas there, and it meshes with the other stuff too. This all gets rather complicated, doesn't it?