Two Sets of Rules, the Good and Bad?

[MaxWilson]

The DMG specifically says how to calculate CR. It says "include these factors". Including anything else is a houserule.

AFB, but you might want to re-read the final steps of the CR calculation because no, considering additional factors is NOT a houserule, it's just something with no guidance given beyond the fact that you should do it. Explaining how they derived the existing guidance for Nimble Escape, Legendary Resistance, etc. would help in extrapolating guidance for other things, like the ability to steal memories and warp enemy spells, or sunder weapons.

And in building this using PC rules, you've spent 5-10 minutes writing down a bunch of details you'll never use.

Does it really take you 5-10 minutes to write down "Diviner 7"? Or is it the spell list that takes you 5-10 minutes to write down? You need that spell list no matter which approach you use to NPC creation.

I think now we know why NPCs with classes are so hard for you, PhoenixPhyre: you're doing unnecessary work.

Not to mention it's a bad monster, as are all such glass cannons. Because it comes down to "did it go first?" Then someone's going to be seriously hurt. Otherwise, it dies without putting up a fight at all. Likely won't even get a turn.

I guess you must really hate the 45 HP CR 7 Drow Mage in the MM too.

Well, that's a revealing comment. It says a lot about how you run your game: Combat As Sport apparently, with NPCs whose presence onscreen lasts for approximately six to eighteen in-game seconds. I play Combat As War (sometimes hybridized with DramaSystem), and NPCs are meant to have an onscreen presence that lasts between minutes and years--otherwise they'd be monsters instead of NPCs. No wonder we build NPCs so differently.