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