So if I can catch the power-scaling discussion in the thick of it, i'm gonna go ahead and bring up a point that I haven't really seen touched upon, but i'd like to reiterate in a hinted-at point in the introductory post:

Power scaling works both ways. 

What I mean by this is that making the most omnipresent, powerful character isn't necessarily always even the best course of action. Making a demigod that will blow up everything with the snap of a finger is bound to cause a lot of attention. Being the God of the Lyches and having an army of undead is great and all, but use too much force, and you'll make yourself a big target. Make yourself a big target, and now congratulations, you turned killing an unassuming teenager into getting a seventeen nation coalition on your target because now there's an angry Evil Wizard out on the loose who's going around blowing up villages and Lord Ahriman's cover all willy-nilly. And that just won't do. 

Now, this isn't to say that you shouldn't make powerful characters. It's me saying that you should consider other approaches, and that you should consider the fact that - in general - the more powerful you are, the more you get noticed. The more powerful you seemingly are, the more people talk. The more people talk, the more attention is painted onto you, and the more support you unintentionally give to Protagonist-kun. The more support you give him, the harder your job gets. Blending in, seeming innocuous, and overall getting rid of the Isekai Protag before anyone knows they're a big deal is often a far better way to go about it than to go all Rick Astley-era World Wrestling Foundation on their ass. 

Also in a way, the machinations of Her Guidance[sup]TM[/sup] - if it wasn't clear - oftentimes makes it such that a well-laid plan is far more valuable than any display of superhuman strength or eldritch magic. In this way, sometimes it's actually [i]more[/i] of an advantage to just be a regular anybody, since your average dude on the street is way less likely to be seen as "The Agent of the Demon Lord" than, say...some living demigoddess or an Anubis-sorcerer.

So please, use some discretion. Sometimes, having a character who's actually a lot weaker in power makes them likewise a far less susceptible target, which is what you may end up wanting in a lot of cases.