Really liking your suggestion for Medica 2, and the proc effect would be fantastic. Perhaps lower it per tick though? 16% for each tick over the course of 15 seconds (assuming the hot would revert to its original duration) is a bit gamebreaking imo,.
Another thing I had suggested for Cure3 was to add the proc onto Cure 1, forcing us to choose between a free Cure 2 or half-mana Cure 3 for that proc.