The usual frost troll you encounter when climbing high hrotghar, somehow obtained ancient dragonborn aka invisible race immortality.

a bit chit-chat, i want you guys to know how i feel, please read

I was using the troll to train destruction and restoration skill, i didnt forgot the well rested bonus, but foolishly forgot mage stone. so i thinking going to guardian stone, dont know why, at that time i feel like playing the game in a........what you call it? immersive? epicness? kind-of-play....

so then i "wuld-nah" then sprinting, armorless, clothed though, no not pervert or streaker

thats after i casted ash shell spell to the troll

"aaaa you cant chase me, sandy troll" was what i thought at the time, while smiling like idiot....

gotten pretty far, probably less than 30 sec, so maybe the troll still ash-shell-ed

i fast travel to guardian stone, then to whiterun(well rested), i quicksave like 5 times......

get back to the troll....and....you know what happen

what happen

At first i though the troll has had infinte health, still wondering why.....

then i realize my flame spell not inflict burn effect, i tried ice and lightning, dont work

physical dont work

ice form shout dont work

fus ro dah dont work

begining suspicious.....

tried fireball.....i think dont work

tried fireball again....i realize the spell didnt explode

again.....eh? why is the explosion......

again........seems like the spell goes through the troll.......

again.......confirmed

but im not giving up yet !

duhnevir!

the ghost got owned

drain vitality no good

the decaying dragon beaten, but the troll doesnt feast on him, being picky with the meat are we?

odahving no good either

same with rune, cloak, cyclone shout, marked for death, drain vitality, bash, arrow, bound weapon, conjured creature, ash guardian, exploding bolt

yeah, the rune didnt trigered, its as if the troll doesnt detected

like the throll become ethereal with no ethereal effect, yet capable of inflicting harm like ancient dragonborn from dragon aspect

and so i set up the two, resulting in a........empty brawl?

tried kill on console too, dont work

no the troll doesnt have visual effect like in ash shell-ed state, just normal frost troll

i havent tried bloodskall though,

unconfirmed either whether the troll is affected by the ground shaking from dragon landing or not

and other save before that just fine, the troll is slain-able

i havent tried reproduce the same pehomenon on other enemy too

probably can immortality-fy meeko?

now i have ancient sandy-ed frost troll in my save, i dont mind, so i continue my game, but now its bugging me, im curious, regret, come late

has anyone encounter this bug or glitch ?

or has any idea to solve it? or what truly cause it?

or even know how to fix it?

gosh my languange, forgive me