So, everyone by now knows that the only thing Swain's soul frags do is make his ult burst harder. This is great, but it feels like it should impact your gameplay more, and that the Swain player should be rewarded for having landed their W and passive. What if each individual lightning bolt was increased by a certain percent per soul fragment. This wouldn't necessarily make his Q start blowing up the world, and base damages could be tuned according to time spent at full soul frags, but it would give you an incentive to stack them up fast, and really think about whether or not you need to ult in a certain situation.
Example: 1 soul frag increases each bolt of lightning's damage by 3%. Total, 15% more damage on Q if he shotguns you with it, scaling up to a total of 75% bonus damage with 5 soul frags, provided you land the whole thing. Again, the base damage could be adjusted to that, but it would give Swain more decision making around his Frags and using his ult.