To level up and get a lot of gald fast, defeat an enemy called Mimic Giant. You have a chance to find it from any treasures when your average party level is 76+. Mimic Giant gives you about 3000 EXP and 35,000 Gald on Hard difficulty. 35,000 Gald is not a lot, however you can multiply the amount simply by using an item called drop bottle, you can get this item from Lohgrin and Dark Turtlez shop (You need 3 stars or above to make them available).
In the battle make sure you use 15 drop bottles before you kill the giant. Use the bottles at the early phase, because mimic giant will try to escape if its health is low
At the end of the battle, you should get about 1 million gald, make sure you spent the gald first (before doing anything else), because the cost of the teleport depends on your current gald (unless you have already unlocked the 0 0 gald travel cost on your lord of the land).
There are few places which have a lot of treasures chest near the save points, which will make the process of farming mimic giant easy,they are
Note: Make sure you have treasure rarifier and restoration boon on your lord of the land
To boost your gald from mimic giant even further go to Lohgrin and choose “Deep fried Prawns” at the inn keeper.
As for XP go to Katz village and talk to inn keeper and choose the food which boost your XP if you’re able to deal certain amount of damage to the enemy. If you can’t see these foods now, simply keep sleeping at the inn to increase its level.