An interesting idea. Not sure what to make of this "Sea of Eventualities" either. Smacks of a kind of secular or fantasy predestination thing imo.
My take on it probably sounds crazy, but here goes.
From what little I can understand about quantum physics (which isn't much) perhaps more accurate might be 'Realm of Probabilities' -- some more likely than others, but in theory...
So maybe 'magic' is a spell caster somehow being able to understand, or manipulate this quirky sub-atomic realm, and then conjure up an ice spike or something. But killing enemies outright...
...Maybe that would be too complex, take too much energy, or the 'outcome' (eventuality?) is just far too improbable!
Hope that made sense. ; )
One of my favorite Sci-Fi writers is Kim Stanley Robinson, and (wish I had the copy with me) in the Mars Trilogy he talks about something he termed "coincidentality." As I understood the idea, it all boils down to random chance.
A Wild Mage's fireball kills everyone in a tavern except a guy who was bending down behind the counter to get a big iron kettle or something. What are the odds of him doing that at the exact moment in time when the fireball exploded? So people will no doubt tell him, "Wow! By Melphas! You're lucky to be alive!" And who knows... maybe they're right!