That's an interesting approach, but I was going to change 'enviromental guardian' to a sort of guardian figure for the god-king at the time.
Works like this: Anyone could have used the well, and anyone who DID use it would gain a fuck-ton of power just by contacting it (like a 10-15 level BOOST).
God-kings are more common than one might think, as the well recharges a lot faster (think 50-100 years instead of 1000). So some of them use their new power to gain immortality and try to rule all (Lord Ruler) some might take their new power, and use it to rule others justly (Lord Nasher from Faerun) or could just take the power and go dick around (James the Wanderer) or use it not to rule, but to serve in a greater way (Medivh from Warcraft 3).
more or less the person decides the power, and some people FUCK THINGS UP, some help to fix it, and others twink it to fit their needs/wants better (ie. Elves were created by someone who didn't trust magic, and wanted a bad-ass protecting him. one guy made inquisitors, another made... etc.)
When using the well, they basically have infinite power for about ten minutes. Then they just become a bad-ass, not omni-potent.