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