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