Prillian adds new features to phpBB that are similar to an instant messenger service (like ICQ or AOL Instant Messenger), while still being part of your forum. These features are typically accessed through the "IM Client." The IM Client is basically a new browser window that uses combinations of HTML and JavaScript to provide a central place for accessing controls and receiving messages. Individual board users are not required to download any software to use Prillian. Prillian runs through web browsers like Internet Explorer, Netscape, etc.

Prillian's features include user preferences, admin panel and configuration add-ons, a buddy list, an ignore list and full support for normal phpBB features like BBCode, smilies, etc.