Typically this would be done using HR Criteria on the Activity itself. Without knowing your use case, I do not think this is a good employee experience because the activity set would show on the LE Dashboard, but may not apply. Remember activity sets show in the dashboard regardless of the advanced trigger, or any trigger type for that matter. I think the best option would be to structure the Activities so you can use HR Criteria instead of trying to dynamically trigger activity sets.
There are use cases where an activity set needs to leverage Advanced Triggers, but I am not certain this would fit given your example. If you can give the use case, there may be a better way to accomplish this.
Regards,
Mike
