Level Units A Bit More Before Promoting
Units in Fire Emblem Echoes can be promoted once they reach a certain level – once into a middle class, and then again into their ultimate class. However, it’s a better idea to keep training these units a little more before promoting, maximizing the stats gains they can receive. As units get higher in level, they’ll start to gain experience at a slower rate, so you don’t want to go overboard with this unless you’re determined to grind and get each unit to level 2o.
Once they’ve reached that threshold for promotion though, use them a little bit more in battle and gain a couple levels before heading to the Mila Shrine. Especially as the game gets into its later segments, enemies will become much tougher, so you’ll want the strongest units possible.