Unique but modular class abilities

The Problem

The unique character abilities are one of the largest challenges I've faced in this project.  I want to create a system for abilities that can be modularly added and taken away from characters, but the challenge in-lies in the fact that each of these abilities is not only going to have unique triggers but also unique effects ranging from dropping items on the ground for other players to interact with to overflowing your guns magazine when you reload after a kill. These unique triggers pose a problem to modularity. I need to find some common ground for these abilities so that I can create a generic storage structure for them. 

The Solution
As I am still doing research and actively developing the solution to this problem I can only pose my working theory. I believe that if I create a component on the character that houses references to the player itself an perhaps the inventory of that player I can subscribe to base events set up in the player and funnel those into events that take in parameters from those references. This will give me an attribute set that I can modify and change based on the predetermined nature of the  ability.