#FEHホームで最後尾左の英雄に最後尾右の英雄の服を着せる
This translates roughly to #FEHDressTheHeroOnTheBottomLeftWithTheClothesOfTheHeroOnTheBottomRight

Inspired by pool #13922, this is yet another Twitter-based meme. The two randomized Heroes found at the bottom of the Castle's Home Screen are found, and then you draw the character on the left cosplaying as the character on the right.