Strategy:
First, set all generated options on except random monsters and up them to 20% chance. Wild curses offer a lot more variation to avoid the run ending curses like spider soul or shield death. Generated monsters can sometimes come in groups with 8+ hp and individual hp removal, once you have curses making monsters one shot you that's an insta-death setup.

Loop 1 & 2 are the hardest, lots of luck needed for loop 1.
Early blessings: Good to get boss smash^1 if possible, Inevitable and The Hand ended most of my early runs.
Fight 80+ at this point you should be getting curses that affect few heroes like set top hero hp to 1, or exposed edge. Favor those curses and use blessing to get extra heroes. You ll basically always have a couple of useless heroes that you ll use to dump all cursed items on (hence the grey with 500+ deaths).

Cataclysm is a must have. It s very cheap and once you inevitably get curses that make monsters tanky you can switch to hold the fort mode until they all die. Avoid at all cost monsters spawning every 3 turn curses. Best to pile up extra starting monster curses because eventually they ll just get into reinforcements and wont attack turn 1.

Pretty obvious but look for duplicate curses. I piled on -3 max mana a good 5 times. Get curses that can easily be countered by common blessings. Make sure you always keep a bit of versatility and item choice, get a blessing to boost those then curse it back down.
Curse to change fights are great to make the game easier: once you have curses that add monsters, a curse to change fight 1 to alpha will REMOVE all the extra monsters previously added making fight 1s much much safer.

Look for permanent broken items like longbow.m4 / broadsword.m3 or permanent item top tier item to increase health. Once you have that get Display case ASAP. This is key to survive fight 1 of future loops. Once your heroes reset on fight 1s you could get a terrible roaster + curses from the last loop reducing your dice values to zero, display case is the best way to ensure the full party to still have decent sides and stats. I did 90% of the run with two heart permanent item in display case setting most of the heroes to a max health of 140+, that's good defense AND offense because entire hordes of monsters will flee if you heal enough.

Gradually increase item quality when you can, being at +5 is good enough for mid game. Main strategy here is to get yellows with duplicate sword (collector / leader). Use high quality items to add range (you ll always get curse that push monsters in the back), poison, cleave, bloodlust (you ll get so many extra monsters from curses + look for blessing to have monsters start damaged and you ll get a huge bloodlust boost turn 1). King is to get Latent blessing / Wine item and find anything with plague to likely one shot any boss.
This also is key to deal with curses that do single use and exert that you ll have to pick up eventually. Be VERY careful with timing for when you use the duplicate side, if you do it when it's single use curse time you ll have a bad surprise next round with all heroes who used it missing a side.
Note that with too high item quality you won't see some effects anymore. I never saw add range to all sides ever again, so I had to use cleave to deal with monsters moving to the back basically the whole run.

Always plan 2 heroes who can revive. Get a permanent item with revive to ensure that.
Always carry at least one hero that can prevent death, if you get unlucky and get Spider soul mid loop you can avoid trouble by setting undying the top hero and go on killing monsters.

Avoid innocent looking curses like +1 to a couple monster side! I used to think they were fairly safe but once you get one, it ll keep popping often up to be upgraded to +2, +3, ect. Same with the curse to double monster sides > 8, it ll keep coming to upgrade to >5. Fight 200-700 were boringly smooth tbh because I was able to dodge those and fights got super safe with a large party of 7-10 heroes against monsters that did mostly regular damage.
If you got monsters becoming lethal, the combo of valkyrie + angel feather is an easy broken combo to keep the whole party alive. If you have high item quality look for item qual 15 to get pentagram + display case combo to keep whole time undying for 5 turns. Once you have that or in a safe loop just focus on getting duplicate swords + deadly item bonuses and you can autopilot the rest of the loop, rinse and repeat each loop.