* ** PASSIVE:**
I love it, but in the heal description I would eliminate the word "new", because it make to understand that when you have 5 stacks it won't be able to heal anymore until you ult again.
Too poor mana recovery. I would increase to a 4-5% or maybe do it a higher proportion but according to the missing mana.
First, the damage description is awful. Please, let us know how much damage does to champions, and then say less 50% to other enemy units or the number if you want, but damage to champions is priority.
Second, too slow. I have 2 ideas: or make it 0'2-0'3sec faster, or put a recast, where after 1'5sec (for example) you can press again W to detonate, or let that eye like a ward for 3 sec until it explode. (Maybe too op, I am not a videogames creator, I just love Swain)
Maybe it should go through minions when it come back, and only roots champs.
I love it too... although I miss the monster form, please, keep the bird head and dont make to pay for it in the expensive skin.
**DESIGN TIPS:** When Swain can detonate her ult, I would add some kind of black to the particles (not only red and more red over red, but red and black, maybe like smoke, in his northern skin could be in white color, or black too). And the birds in the map doesn't look like demonic.. pls resalt their eyes, they are a really cool detail!!