Kythos, the Corrupter

Here is my champion concept for Kythos, the Corrupter. Kythos is a mage who uses dark magic to deal heavy damage to both his enemies, and himself. Here's the link to my post of him on my Deviant Art page: http://evalgan-art.deviantart.com/art/Kythos-the-Corrupter-Concept-Art-570334260?ga_submit_new=10%253A1446696093

Lore Long ago, what is now known as the Shadow Isles was a quiet, peaceful place, where magical energies gave the forests life similar to our own today. There were villages full of people who coexisted with nature in perfect harmony, but there were others who were only disgusted by it. Others who planned to erase this peace the Isles shared. The only account of this ancient land that has been acquired came from Maokai, who was saved by the forest's spirits. That was, until Karthus discovered a strange, ancient stone tablet on one of his journeys to the Isles. He deciphered it, and found that it led to much, much deeper secrets than ever realized. The tablet detailed an area in the center of the center-most island, where the three mages who corrupted the Isles were buried. Karthus decided to see what would happen if he went there. He found three pillars, each with a slot in it. Each slot was shaped differently, however, one matched the tablet Karthus had. Karthus placed the tablet into the pillar, and it crumbled, and out stepped a rotten old corpse of what used to be a man, corrupted by dark magic beyond anything anyone had ever seen. The Corrupter, as he called himself, wished to learn more about the modern world. When it was suggested to him that he join the League of Legends to learn more, he quickly accepted. Only he knows his true motives, however many believe them to be to do the entire world what he had taken part in in the Isles long ago.

Basic Stats Range: 550 I suck at stats, so range is all I'm gonna do.

Kit

Passive: Corrupted Touch > Kythos's basic attacks each apply a stack of Corruption to the target. Some of his abilities will remove stacks from opponents, others will apply stacks. Killing an enemy with stacks of Corruption will apply all the stacks of Corruption to Kythos. Corruption applies debuffs based on the number of stacks applied, and will apply the same debuffs to Kythos, but will require twice the number of stacks to progress on him. Stacks of Corruption will last 6 seconds on enemies that he is not constantly interacting with.

Debuffs: 1+ Stacks: takes 2% increased damage from all sources 5+ Stacks: deals 2% less damage 10+ Stacks: takes 4% +1% per 10 stacks more damage from all sources 15+ Stacks: deals 4% +1% per 10 stacks less damage 20+ Stacks: takes 5 true damage per second 25+ Stacks: all abilities Kythos uses on the target gain a buff For Kythos, it's all the same EXCEPT 10+ stacks for tier 2, 15+ stacks for tier 3, etc. Having 60 stacks will cause all of the Corruption debuffs on Kythos to turn into buffs. Having over 100 will cause his abilities to apply their bonus effects to all enemies, regardless of the target's number of Corruption stacks.

Q: Corruption's Embrace >Kythos applies 1/2/3/4/5% of his current stacks of Corruption to all enemies in a targeted area and deals damage to them. Enemies with 25+ stacks are also stunned for 1 second. Damage: 40/60/80/100/120 (+65% AP) Cost: 40/50/60/70/80 mana and 5 stacks of Corruption. Cooldown: 5 seconds.

W: Shadow's Envy >Kythos pulls in energies from the surrounding area, channeling to gain stacks of Corruption at a rate of 2 stacks/second for up to 3 seconds. At the end, he deals damage to enemies in the area. He gains 4 stacks/second instead if he's in the jungle, and 6 if near the Baron pit. Enemies hit with 25+ stacks are silenced for 0.5 seconds Damage: 20/30/40/50/60 +50% AP +0.5% per stack of Corruption Kythos has. Cost: 60 mana Cooldown: 20 seconds.

E: Corrupted Corpses >Kythos eats the corruption of his enemies, stealing stacks of corruption from all enemies in an area around himself and dealing damage to all enemies hit. Enemies who had 25+ stacks who are killed by this ability revive as weak corpses, who will attack the enemy with the most corruption, prioritizing champions. The weak corpses have low stats, but they increase based on the number of stacks of Corruption they had in life. Damage 100/140/180/220/260 +40% AP +10 damage per stack stolen Cost: 90 mana Cooldown 15 seconds

R: Dark Pact >Kythos shrouds an area in corruption. All enemies within the area take damage every second, gain 1/2/3 stacks of Corruption every second, and are slowed by 25%. When the duration ends, all enemies within the area are stunned for 2 seconds and take a burst of damage. Enemies with 25+ stacks of Corruption are stunned for twice as long. Damage 30/45/60 +10% AP per second Burst damage: 250/400/650 +100% AP changed to 250/350/450 +80% AP +3% 1.5% per stack of Corruption on Kythos. Cost: 150 mana Cooldown 140 seconds

So what do you guys think of Kythos? Any feedback is always appreciated.