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