By opening the chat (default keybinding: Enter) and prepending a message with “!” you can create a dice roll through chat. They follow the same system as the dice URLs and as such contain the same features. For the full description of what is supported and how exactly, please refer to that article, but here’s a short run down of examples with what is possible:

• !1d20 Normal dice rolls

• !Rapier:1d20+4 Named dice rolls, modifiers in dice rolls

• !2d20-4+3d12 Several different dice types in one roll, modifiers

• !1d20+2/1d20+2 Two separate dice groups (that are separately summed up) in one roll, modifiers

The system is subject to the same base limitations as the internal dice rolls and the URLs:

• Per dice roll the maximum number of dice across all dice groups is 40.

• Currently labels/names on several groups isn’t supported (only the first label specified shows)

• Not all possible arrangements with basic arithmetic are properly supported, eg: !7-d6, which drops the 7 at the start

• More features are definitely planned like being able to drop the lower or higher of two dice, …
  This is just the first iteration.