In the rich text editor:
@FellDragon
In a comment:
[FellDragon](https://chowlings.com/user/FellDragon)
For Names and Avatars:
In the rich text editor:
%FellDragon
In a comment:
[![FellDragon's Avatar](https://chowlings.com/images/avatars/default.jpg)](https://chowlings.com/user/FellDragon) [FellDragon](https://chowlings.com/user/FellDragon)