In the rich text editor:
@scyllaelus
In a comment:
[scyllaelus](https://chowlings.com/user/scyllaelus)
For Names and Avatars:
In the rich text editor:
%scyllaelus
In a comment:
[![scyllaelus's Avatar](https://chowlings.com/images/avatars/2066.jpg?v=1678286435)](https://chowlings.com/user/scyllaelus) [scyllaelus](https://chowlings.com/user/scyllaelus)