You died while having only F+++ and rcorr in addition to what your char started with.
Not even C+ while facing an Ice Fiend.
Only N+ while facing several tormentors.
A garg has such an easy time to get max resists.
Against 1 or 2 tormentors + popcorn it will work.
Against anything else you rely on bad monster behaviour (like: moving towards you).
The monsters on the screen aren't popcorn and the spells you have will leave them several turns to cast/attack while they take damage.
Skilling:
Spellcasting to 25: this is very expensive.
air+earth: 27 is very very expensive. I guess you wanted to get the max power from your main spells but as soon as you hit 2% (or whatever) stop skilling that and skill something else.
Positioning/Fighting:
Your spells are loud. Very loud.
They will attract more monster.
It is ok if you are in an area where they are in limited amount.
Hell #7 is not such a place.
Retreat after you cast shatter several times. Especially since every monster can move now freely (no walls) towards you.
Tornado is a spell for chars with more staying power than yours. Nice as a panic button but it really shines when you can stay in the middle of a crowd. Get the resists (C+, N+++) and as much fighting/dodging as possible when you want to use it.
Items:
Again I guess you wanted to max out Int to get more power from your spells but look at them:
you have 2 items with sinv. Both also give relec which you already have.
This means you're running around with F+, Int 4, MP+9, sinv from 2 artifact items.
F+ you don't even need in Dis (with F++). Is it really worth for Int 4, MP+9, Sinv to use up 2 item slots ?
I don't think so when I look at what you were missing imo.
(I don't even think there are invisible monster in Dis.)
robe: already said.
And finally:
You had CBLink at 1%.
Use it
You can even chain-use it to get back to the exit.
There is no reason fo this char to get into that situation.
This char may have looked invincible (and pleasing for the player) for a long period but it is not.