Day 1
Duchess’s base HP is insanely low, where normal characters can get away with going to a cathedral or fort, she cannot. Level up to lv 2 or 3 and then go there instead.
If we are near a Church, go there. Churches give you extra flask charges, and Duchess needs all the help she can get early on.
Fort’s are also great early settlements to go to because the enemies and bosses are fairly easy to deal with, and they always include a map for the location of talisman beetles.
There are some insanely strong talismans for Duchess, especially the ones that buff spellcasting, so going out of your way to get them is never bad.
You can also decide to go to a Main Encampment to find a shopkeeper and a smithing table who tend to spawn there often. There, you can also defeat the boss for extra levels. Usually aim for level 5-8 after day 1 to have a good setup for the boss and day 2.
Keep in mind that you can always find a staff inside a fort. This will help you get a better staff by defeating a boss later.
Day 2
On Day 2, we want to start looking for either a Field Boss, Castle, or Ruin. We can run towards a Crater if it spawns, for Duchess, it's not needed, however, and is 100% your choice.
Keep stacked up on consumables, but don't be afraid to burn through them. Once you have your desired weapons, if they need upgrading, get a shard from one of the mines. You should be far too strong for the boss in there, so that should be a breeze.
Keep looking for weapon passives and try to get as high a level as possible for day 2!
If you have trouble finding a good weapon, try the castle in the middle. There is a boss at the top of the castle, and at the bottom, they both drop purple tier loot, usually, so you should be able to get a good weapon from that!
Day 3
With this guide, we are taking into account that you fight the boss Gladius.
Be sure to check the shop and level up before you enter the arena!
Gladius is most dangerous at mid-range because of his swipe attacks with his sword. If you have trouble getting in use, keep in mind Duchess can double dodge because of her passive.
The risky part for her is phase 2 because she has no real way to deal with the triple wolves' attack, so use your ultimate for that if they focus on you!
Keep in mind to use Restage whenever you deal heavy damage to the boss to double that amount, this is essential to using Duchess to her full potential!