This is not my campaign, but I proposed the initial concept to the DM and they told me that the outcome at the playing table was outstanding.

The underlying campaign uses various Immortal house rules that for example require Immortals to have a number of worshippers as big as possible to have more power (a bit like Blacky's proposals and ) or die / fizzle out if there are no more worshippers.

My suggestion was to implement CM6 Where Chaos Reigns in Blackmoor/Mystara (that's my only contribution).

As a player I enjoyed a lot Where Chaos Reigns, that is a module about a race of supertechnological aliens (the Oards) that do not worship Immortals and do loath magic, but rather stick to science phylosophy and Technology. By the way, they developed time travelling technology (although it is incredibly expensive due to enormous energy required).
The other concept that comes with Where Chaos Reigns is that magic and Immortals are totally intertwined, so without magic there can be no Immortal (and vice versa, I guess)
Of course, if you put this in context with the house rule of Immortals that die when they lose the last worshipper and are anyway very weakened when their worshippers diminish (effectively, they lose Immortal levels!), it becomes very clear that the time-travelling and magic-denying Oards are a massive danger for them.

When the Oards, after winning over several systems, focus on Blackmoor/Mystara, the local Immortals panic, as they have strict rules on interventions on the Prime Plane (enforced by the Elder Ones, that se these events as an effective test of the Immortals) and therefore they need to do it through the players (otherwise we wouldn't have this adventure! :mrgreen: )
The Oards act with stealth like in the other planets where they obliterated magic and the associated Immortals by tipping the balance of past historical events when magic was about to be discovered / developed by some civilization and make sure that other, non-magic civilization obliterate them before.

At this point Mystaran Immortals, through The Comeback Inn 8) , send the characters in the past and negate/counter, one by one, all the various misdeeds of the Oards done at different timelines (adapting / replacing the various scenarios proposed by the adventure module with Blackmoor / Mystara alternatives), until they can gather enough information to attack the very Oard base, set in a special "dimension" outside time and space (the Entropy Bubble), out of the reach of all Immortals.

That's where the campaign is now and my next suggestion for the DM is to allow the characters to find evidence that originally "this" universe was devoid of magic and Immortals but dominated by Technology and Phylosophy and that actually the Immortals came from "another" universe to bring with force their approach (turning this way effectively the Immortals into villains and the Oards into the "Guardians of Galaxy") in a "everything you know is a lie!" plot... just to see what happens :lol:
But I don't know if this will be implemented on the playing table or not.... we'll see :wink:

Well that sounds fun!