Basically after X point in the mod (maybe opening first portal) you start to attract the attention of one or more elder ones. At first you'd be little more than maybe a fly buzzing in their metaphorical ears or a slight itch. As such, you may find yourself with random debuffs (dependent on who has noticed you.) As you progress, these can be can be lessened and you may see yourself get the occasional buff. Certain actions

Would increase or decrease their noticed based on who like / dislikes certain actions. Oh, their actions would only effect those with necronomicons of however much affinity to a certain elder one. (They bind to play, right?)

But if to much notice is made server wide by a specific elder one, then there is a chance that a "mental projection"(because if any showed up in the flesh, we'd all be screwed) will be spawned somewhere in the overworld (limit 1 at a time per elder one) and just start destroying the world. Blocks, mobs, players. Somewhere on the scale of mobzilla or something.

I'll look into this. It would make a good addition to the different statues and charms, providing you with benefits from showing devotion to a single one.

What do you think about shrines? Could be used as a means of showing devotion while reducing the chance of some bad things occurring. They would require that you place a certain amount of blocks in a certain pattern, and then have something to activate it (could be that you activate it for a period of time, then have to do use the same method to activate it again).

I like it. The offerings would have to be different for each one I think. The structure can be different for each as well if you really want to go overboard, but I think that the separate offerings should be sufficient. Of course, changing up who is worshiped in the shrine would have bad consequences. The controller block used would need to be able to retain this information to prevent players from simply breaking it and replacing it to change up who it is that is being worshiped using that block. The controller block would also have to be suitably expensive to dissuade players from just changing out controller blocks if they want to change up the elder one.

As info I mean (and nothing final of course) like lets say you do a bunch of Cthulhu offerings, then you decide to do one for X. The bad effects you would receive for doing so would be much worse that someone who frequently gives offerings to a variety of elder ones, if any. The trade off being that the person who does a lot of switching would only be able to get tiny benefits in comparison.

Oh. And/or you could have it tracked by player. With an X amount chance of an elder one finding out that they are being "cheated on" by a player going to another shrine.

The player who manages to get to a high level with several would live in the fear of knowing at any time, any one of the elder ones can take notice of their behavior and be punished for it. Mwahahahaha

So the new Darklands-creation ritual might score me some points with J'zahar? ;)
Edit: I should have checked the date on this issue before commenting perhaps.