Imo it's inferior to purification. Its lower CD, manacost and bigger AoE is superior, but Purification has bigger damage and WAY easier damage system. In dota, Heal>damage. Damage is reduced, heal doesn't. Omni gets straight 360 heal, this skill gets 285 heal which gets distributed. not really appealing imo.
Concept of single-target damage while healing allies works with this hero, but still i think you can tweak it into something better.
So... It's a +damage over time, which disappears when you get damaged (which will happen often) and then you also get a minor chance to deal a minor portion of damage done to you.
Honestly? from my point of view, too complicated and useless. Bonus damage on one strike is not really that appealing, you won't have enough time to accumulate that when you're focused. Not only that, you don't have the necessary AS to dish out that 20% chance. and 25% damage return is not that appealing imo.
If you still want to develop this hero, i think it's this skill that deserves most consideration. If i misunderstood anything here please tell.
This skill is synergizing and annoying as hell
A cool skill, really. It gives the steroid necessary in order to keep your ultimate raping on the battlefield. And it won't be that imba, considering shukuchi has 4 duration and 6 cooldown.
The main attraction skill. The dps is fun actually, but do note that 80 dps at level 6 is extremely painful. And i don't really see the increase per level that appealing (+10 damage, 5 damage increase, 5 damage to those who attacks, -10 cooldown).
Maybe increase AoE per level?
So... Ulti basically allows 100% tanking, and 3rd skill gives the necessary HP while you burn down the excess mana with 1st skill, dealing bonus damage to those pesky carries that just have to die. 2nd skill though, i don't understand what does it contribute to you.
Burst damage that has to be charged for a long time. It's good for one use only, and it disappears if you get damaged. It does serve as another reason for enemies to keep damaging you, but the damage is just not appealing. 5 bonus damage per 4 seconds. lol.
The other stuff. Returning damage you received. Nice concept but stated above it has low chance and your AS is even lower.