[Baalz]

Nehekara is a strong nation, but I don't think they're overpowered compared to other strong nations. I had some good luck, and played a good game while honestly you guys were struggling to leverage the really effective counters available - and remember, I never fought against anybody who wasn't much smaller than I was so most nations would feel overpowering in that scenario. Bone scorpions are not very scary at all if you deploy a counter to them, and counters are easier and cheaper than the bone scorpions. Remember, those guys are expensive, unless I'm already winning losing a couple of them could easily be a drastic blow to what I've invested in my army. I don't think at any point there were more than 2 (maybe 3?) deployed against any player, so it's a bit of a stretch to say that anybody was swamped in them. Here's a couple ideas of what I would do vs bone scorps.

Crushers are size 6, poison and fear immune.
They lack fire immunity, so a couple fire elementals would pass them out very quickly while being ethereal and size 6.
Tangling vines, prison of fire, even slime. You don't need to tie them up terribly long because...

then

Lightning is awesome at any small number of tough guys. (rough luck your guys default to banishment Eriu)

forged bows: just man's cross, piercer, vision's foe, ethereal xbow, thunder bow are all 5 gems and a few of any of them would ruin this shieldless guy's day.

Undead/construct counters: dust to dust will tear them apart and is trivial to field for anyone with D1 mages. A couple herald lances will ruin their day (or solar rays). Holy scourges/flambeauxs or smashers on any light thug will disintegrate them.

Their MR is fairly low on the thug scale, a couple guys with penetration boosters spamming control the dead could have fairly easily snatched them.
Or any of the other nasty MR-resist spells, of course.

There protection/hps aren't *that* great. They would have been torn up pretty fast in melee if I had used them much against the ogres or dwarves.

Keep in mind, the bone scorpions are very similar to Behemoths buffed with iron warriors - only three times as expensive. The regen, admittedly is quite nice, but then again more than 3 times the hps will go a long way as well (if you were using behemoths).

Tomb kings are not functionally immortal. Their second form is drastically weaker, so you most certainly do not use them as a "I don't care if they die" unit which is the strength of immortals. Their second form is also weak enough to make thugging tricky. They also have pretty low hps so are only mediocre thugs even in their first form. Sure, they're effective for raiding PD...but that's a low bar for a 500 gold unit with a bunch of equipment and alt research.

I'll write up an AAR/guide and share my thoughts in more detail.