What units have the most interesting/unique skills?

Just looking for units that will add some sort of flavor to the game for me, which for me currently is just autobattling with E!Sigurd. To be clear, the skills don't have to necessarily be strong, but just interesting or unique. Marianne's Refine (Sing during Canto) and Grommel PRF's self-damage are good examples of what I'm looking for. Thanks for any suggestions!