In the rich text editor:
@Jelli
In a comment:
[Jelli](https://painted-relics.com/user/Jelli)
For Names and Avatars:
In the rich text editor:
%Jelli
In a comment:
[](https://painted-relics.com/user/Jelli) [Jelli](https://painted-relics.com/user/Jelli)