Wow, i forgot how extremely brutal the Infinite Dungeon could be.
I have been running several failures so far, but my latest character (Shalore Alchemist) was doing -very- good, it surprised me (though far from my best character a few versions ago , a bulwark that died at depth 30) .
If you never played the Infinite Dungeon gametype, it's a classic dungeon crawling experience, no adventure/campaign, only various randomly generated levels with various kind of monsters, elites and bosses and vaults.
An interesting fact about Infinite Dungeon that prevent boredom is that you gain experience faster than usual, roughly clearing 1 depth can gain you 1 level, but challenge increase at each depth too, so you really need that experience, leading you to want to open the vaults sometime, as monsters in there can add a lot in experience and you can end with one more level and sometime good items.
Clearing vaults early can then help you to get better prepared for the lower depth, but, Vaults in the infinite dungeons can be -a lot- more dangerous than the adventure gametype vaults, it looks like the random generation does not really care about the danger level around, so be cautious and be sure to have ways to escape quickly and run to the stairs in case insanity appears in there.
Another problem of the infinite dungeon is that you find much less items than in adventure in comparison to how fast you advance in level and power, making it a lot harder (due to you needing a lot of real luck) to get yourself good items or artifacts, another reason to explore those insanely dangerous vaults.
So back to my character, he was doing good and had cleared 2 early vaults, so i was roughly at level 16 when i entered depth 15 (a Shalore has a 25% experience gain penalty, so it's very good to be level 16 at that point).
Due to the smaller item distribution at that point i still didn't found any teleportation rune, the only escape possibility i had was a phase rune that was given to my character at the start. And my equipment wasn't really so good at that kind of Infinite Dungeon depth, but from past floors i thought i could still manage as long as i don't try to open any more vaults.
And while looking at clearing the floor, i landed into a room, my golem immediately fired his laser beam and exploded 2 turns later, i noticed why at the limit of my field of view : Epoch and Shardskin appeared.
What ... Epoch + Shardskin ? ... that's just plain insane.
Epoch is a temporal elemental boss, so without elemental resistance, you're in for a huge problem (and guess what ... my character had found 0 temporal res items)
Shardskin is stronger, it's the alternate boss of Old Forest, and is immensely more dangerous than the normal boss of that dungeon (Wrathroot), usually the best survival tactic when meeting Shardskin when you're between level 14/15 (the usual level you are when you're doing Old Forest) is to simply escape and go do other dungeons until you get more levels and so more talents/skills because you really need them to avoid taking a huge risk facing that boss (while if you faced Wrathroot you should have not too much problem at such level)
So basically my character was done for, and indeed my shield exploded that turn when i saw the 2 bosses appearing, while i lost half my health.
I used then the only way i had to escape, the Phase door and appeared right next to Epoch. And died the following turn.
In Eidolon, i rebuilt the Golem, and went back, i used the Phase door immediately of course, letting the Golem to delay the 2 bosses.
This time i was lucky and landed in another room, while my Golem was destroyed again 2 turns later.
I moved as away as i could, only to see Epoch appearing (the damn thing is not only insanely fast but it can teleport).
Of course, the phase door wasn't up yet, and Epoch was simply laughing at my bombs, destroying my shield then myself after several turns of me trying to get away then being pulled back by some of Epoch skills.
Eidolon again, rebuilt golem and went back.
Epoch had some trouble killing the golem quickly (i guess most of the damage was made by Shardskin then), so he was able to tank for me, while i was bombing and staff shooting him, but the damage we were doing was not enough in comparison to how much he was damaging the golem, i was thinking about running through a corridor , trying to locate the stairs so i could escape this hellish floor.
But before i reached that corridor, Shardskin appeared.
Without even trying, i just decided to escape with phase door, only to land at 3 tiles from Shardskin and farther from the corridor i hoped to reach ... looks like when ToME4 wants to destroy your character, the game does not have any mercy.
Of course, the shield crumbled from the death rays, and 2 turns later, my then hopeless character exploded (a turn after my Golem died so i couldn't even try to drain my golem life to heal, as of course, no heal and no regen runes have been found up to now).
At that point, i gave up at Eidolon, no point in testing more my luck in this impossible escape from unescapable bosses.