How can you grind?

Solution 1:

I've found two ways to grind my units up to overpowered levels.

In the earlier Acts, you can simply go into dungeons and enter/exit the Mila Shrine area to reset the enemies. Making sure to get a preemptive strike before the fight will make the grind slightly easier, especially if the enemies are far enough away from each other that they won't group up into one fight when you attack one of them. The main drawback to this is that your units will eventually become fatigued. This is easily remedied by leaving the dungeon and re-entering, though.

The other way to grind is to purchase the two DLC maps that are meant for EXP grinding. For lower level units, you should be using the map Band of Bandages. By the second tier of classes, though, you'll want to graduate to using the Lords of the Grave map.