Darius's Q healing should scale off bleed stacks.
I think its cool Darius can stay alive in team fights with his Q but I think its WAY too strong in short trades and situations where he hasn't really committed to the fight. So, IMO, the heal should heal for a stacking % for each bleed stack. Maybe 2%+another 2% for each bleed stack on them. That way Darius has to commit to fighting his target if he wants to heal and he won't just be able to Q an entire team and heal for almost half his life bar,
The cool thing about this change though is once his 5 stack passive triggers and you get stacks on a group, you could potentially heal for MORE than he heals for now, but it would actually be difficult to set up. I think right now its WAY too rewarding for something that's incredibly easy to do.