Welp... Managed to get to Lethice's Stronghold despite a fair amount of RNG misses at day 55. Most of the game was spent running though... Initially got to her stronghold at level 16.... Was worried about doppelganger and I couldn't think of a good strategy to get past it and couldn't remember if it could be lusted down or not so I opted to just max out stats and get triple attack along the way. Might have overdone the levelling abit because by now I've done a fair number of trials with most of them failures so eh, figured since I finally reached Lethice's stronghold in a relatively short period of time, might as well just grind up a bit more than is strictly necessary. Went in at level 35/day 67, Killed doppelganger via sheer brute force. rest of the bosses fell as per usual, gave myself another day to make heal up and such before Lethice and opened up ascension at day 68.
No screenshots though because I got careless and dead ended myself grabbing the jewelled rapier..... ...... Yeaaaahhh I'm a bit salty over that.
Edit: I challenged myself a bit to make sure not to abuse holiday mechanics at ALL.
Starting off with character creation, I went with a female curvy character for Raphael. Went with the speed perk because there's a LOT of running early in the game to save time. History either Schooling (more spell uses) or Fighter(10% melee damage for maxed out stat damage). First thing you do is try to get the beautiful sword and storage chest asap. Don't even try to fight anything until you've gotten the B.Sword, it's possible to win but it's inconsistent at best, best to wait for the sword and then kill primarily imps. Whilst doing the storage chest runs, don't forget that any dyes you get from beating goblins can be used to offset the hair changes that sand witches do (so you can say yes to them to skip the fight, use a dye to save yourself from further changes (locking out Raphael). Hopefully whilst doing thing you unlock tel adre too. Initial visits to Tel Adre should coincide with proccing Arian's appearance or Dominika depending on the time. if he doesn't show up and boot you out of Tel Adre early on, just keep visiting shop and backing out until he pops up. Also in the desert is an event for a wand, not a bad idea to swap weapons to it if deemed necessary.
Once you've gotten the chest, the overall goal is to accommodate Raphael, do fencing lessons 3 times, then swap to thievery to achieve maximum stat spread (and perks, but perks are less useful), in addition, due to the power boost from fencing and Vulpine Rapier, it's plausible to sell off the B.sword to start amassing some level of stats at this point(personally, I just sell it asap. Just on the offchance I run into Giacomo earlier than expected). The "sub" goal is to gain as many gems as possible and the sky pearl. Which means spamming a lot of explore. Always make sure to kill and sell off imp skulls since they're worth significantly more gems than basic consumption items. Now make sure to keep eating any Succubus Milk/Incubus Draft and Imp Food(optional) you get, 2 main goals with these transformation items, one is large wings so you can avoid some hassle at Lethice's stronghold and the lust point bonus gained from having enough demon form points. Optionally, Goblin form gives a small int bonus and is relatively easy to achieve.
Once you've got near maxed stats (int especially, in fact toughness/int is all you need right now, STR doesn't come into play till Lethice's stronghold...), start exploring the plains. Now you might be asking why this is important, 2 reasons, one, due to a heavy reliance and magic spells, fatigue is very relevant during this time period, Isabella cures this issue and should be recruited ASAP and two, the major source of lust healing, sheep's milk is available in Owca, which you need to explore the plains to unlock. Note that at this level, most encounters are still run for your life, if necessary to fight, Arouse should be spammed rather than attacking magic. Oh, and just submit in Owca's pit. Trying to fight those demons just isn't worth the trouble/grinding time.
Once Owca is unlocked, start working on all the dungeons at once. Factory is relatively easy, the two subdemons aren't strong at all and the omnibus is only strong because of it's health value. She can't really outdamage/outlust you so long as you keep a few sheep milks on hand so just roll over her in a battle of attrition. Deep Cave is a significantly harder dungeon. The first fight is a bit of a crapshoot unfortunately. There isn't a good way to survive through imp horde except with a fair bit of luck.... Spam arouse, hope for the best, this fight in particular is the death of a LOT of my runs.... If overlevelled, the perk regarding fire/ice spells casted cumulatively might work (naturally grey magic too. ... Except you have to go through a harder dungeon to unlock any grey magic.) Zetaz himself is a pushover, and is weak to arouse. Finally Lethice's stronghold I don't really want to comment on since i basically cheesed it with levels/grinding. I'm not sure what a good lowish level strategy would be to get around dopple.... The other fights shouldn't be too hard but Doppel's usually a pain in the butt....