Mixing a bit of TESish magic/divine power with the heroes inspired eclipse heres what I've come up with (note, this is not a backstory final or otherwise, just a general explanation to be built on or discarded.):
Right at the end of the third era, when the blood of Akatosh mingled with the last descendent of the divine talos, the moons Masser and Secunda aligned with the magnus shaped hole in the sky that became Nirns one and only sun, creating a tripple eclipse. The strange interference of the three aligned orbs mixed with the cementing of the liminal barriers and banishment of the portals of Oblivion creates a Dragon break like no other -- six months pass, most of the damage from the oblivion crisis is rebuilt but no one remembers the happenings and goings on of the six months they lost to the dragon break. But unlike other dragon breaks where time jumps forward, this break released an influx of magical energy. This energy is the life force of magicka which all beings can draw on with propper training to cast spells/enchant.
The celestial bodies find themselves "suspended" in time, though nirn still turns on itself to give birth to both night and day, it does not orbit Magnus. We are forever stuck with a perpetual eclipse (though not an eclipse that would cause a total black out, if you have ever experienced one you know what i mean ).
With the majority of magnus blocked (save for a ring that can be seen around the body of Masser) every creature finds it impossible to cast magic like once before -- but some people who found themselves close enough to a "conduit" (Oblivion gate/Altar/the Imperial city at the battle between akatosh/mehrunes) find themselves permanently embedded with the Energy of Magnus. They can draw upon this energy and unlock and use an ability ingraind and unique to them.
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SO yeah, thats the gist of it, I understand that it needs a huge re-write and a build up to make it more co-herent but it does the job its meant to do for the idea thread.
As for abilities, Im thinking it should be an ability the the person may have used before, example: a mage with a mastery of alteration and illusion has a basic understanding of destruction, and uses a thunder spell just as the celestial bodies align and akatosh apears. They would end up with the ability to shoot thunder from their finger tips, but at a hugely amplified level since their energy isnt split between different spells/schools, its all focused into that singular ability.
Another example might be a man who was fighting in the battle of the imperial city, falls back to defend martin, and finds himself perhaps touching akatosh or perhaps bracing himself and wishing time would stand still as the roof of the chapel caves in, he may end up with the ability to manipulate "miniature" Dragon breaks to stop/move through time. (this might be the champion of Cyrodil)
Some one who may have been sleeping/dreaming may end up having the ability of precognition.
Some one running from a horde of daedra may end up with the ability to move at super speeds.
A battle mage healing a fallen comrade might find himself able to heal wounds by touching them.
A person who had entered a realm of oblivion in an attempt to push back the daedra and close the gate might find himself/herself able to move freely though dimensions.
Some one Skilled at sneaking/infiltrating might find himself able to turn into/blend perfectly with shadows or he may find himself able to phase through solid object.
Some one who may have been using a powerfull shield spell might wake up to find himself with "bullet proof" skin.
Thats a basic idea of how the powers work, I'd rather it be situationally based on those peoples past talents or directly related to what they where doing at the time of the dragon break, so its not just something some one made up that has no relevance to the character (such as being able to fly because its a cool power, or being able to move at super speed or have super strength even though your character might have been sedatory old coot of a mage.) But ofcourse, feed back feedback feed back. Demolish my idea and build on it if you must, every thing is wanted and appreciated to try and get this right
As for magic -- it will be non-existant. Magical creatures such as daedra/werewolves/vampires or just about anything who exist because of the daedra will not be able to cast magic on Nirn, but their natural abilities will not be effected since their magical essence is essentially drawn from the daedric essense found in their own blood, which is what made them what they are (depending on your oppinion). But were-creatures may find themselves in a perpetual state of transformation thanks to the moons constant presence.
Another Idea i had was create a few NPC organisations, the mages guild will be dissolved for lack of need, but many of their old members may ally themselves with necromancers/summoners/other magical organisations to create some shadowy organisation trying to hunt/capture/track down these people with abilities so that they may once again reclaim their magical talents.
I also had an Idea for a Khajiit Desert Cult, who have outlawed pro-creation in their race, due to the moons alignment (which has a direct correlation between the Khajiits sub race). This will only last as long as it takes to break the celestial bodies out of their suspended existance. These cult members may hunt down the men and women with abilities, to offer up as sacrifices to Masser and secunda, to provide the celestial bodies with the essence and energy of these perculiar people so that they may again find the strength to move through the skies.
Again, these ideas are as rough as toast. So any ideas, be it an idea for a single ability or many, or an idea for an organisation or an idea that builds on one of my own post it up, all is welcomed and everything can be used.