The Conditions modules brings Condition objects to your project. These are Stat-affecting objects which will automatically set Stats to recompute when added, and will remove themselves from the objects which contain them automatically as well, unless you choose to manually decide when they are removed.
This video demonstrates the creation of a new Condition.
In this video, I show how I'm adding a Condition to a magic spell (which uses the Items module), to apply when the spell is cast on a player.