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