EventManagerAPIDemo.cs

class AbilitySelectedEvent : Event
{
    public uint abilityId;
    public uint playerId;
}

// registering
EventManager eventManager;
eventManager.RegisterForEvent<AbilitySelectedEvent>(this, (AbilitySelectedEvent payload) =>
{
    Debug.Log(payload.abilityId);
});

// triggering
var payload = new AbilitySelectedEvent
{
    abilityId = 23,
    playerId = 0
};
eventManager.TriggerEvent<AbilitySelectedEvent>(payload);