FINAL FANTASY XV MULTIPLAYER: COMRADES

Story related and can not be missed.

Once you finish "City of Light" you'll be sent on a solo mission, and will receive your sigil at the end.

Note: If you completed this achievement from the DLC version of Comrades inside FFXV (it was called "Kingly Blessing" in that version) and transferred your character, it will unlock as soon as you spawn in Lestallum for the first time.