Extra Die
The Extra Die is a special mechanic that allows you to enhance your Active Skill Checks by leveraging a different Attribute alongside your main Skill.
For example, imagine you are trying to deceive a guard with a Speechcraft check, but you have a high WIS. You can leverage your Wisdom score to complement your Speechcraft Check by paying 1 Heroism Point. You then roll an extra, visually distinct d12
for the Check (check the CHA attribute for more examples of Extras).
In order for this extra die to be valid, it must be less or equal than the Attribute chosen as the Extra. If it is, that is a valid Extra Die that can be picked as one of the two for the final total. Note that, regardless if you pick the extra die or even if it is valid or not, it still counts for Crit Modifiers and Auto Fail when applicable.
The Extra Die must be invoked before the roll is made.