Vampire Champ Concept

For anybody who might say "we already got " no, he is not a vampire. He is a hemomancer. I'm talking about a real vampire. So the goals of this concept are to...

-Make an assassin who does not require high mobility but instead utilizes stealth -Convey that it is a vampire -Don't make an unbalanced pile of crap

For the sake of this concept I am going to call this champion Bloodsucc.

Passive: Nourished by Blood Bloodsucc can store up to 10 stacks of Blood. When he kills a champion he gains a stack of Blood, but he can also attain blood by using his abilities. Upon reaching 10 stacks of Blood his next** Vampire's Bite or Kiss of Death is greatly empowered. The empowered versions of these abilities consume all 10 stacks of Blood**.

Q: Vampire's Bite Bloodsucc bites the target enemy. This deals 70/120/170/220/270+(80% ability power) damage. If this kills a minion or large monster Bloodsucc gains a stack of Blood. Killing a champion with this ability grants Bloodsucc two stacks of Blood(on top of what he gets from killing them.) He will also be healed for 30/60/90/120/150+(40% ability power) damage if he kills a champion with this ability.

Empowered: This ability will deal 100/160/220/280/340+(90% ability power)+(5/7.5/10/12.5/15% enemy's missing health) damage.

cooldown: 8 range: 175

W: Cover of Night Bloodsucc becomes invisible for 3/3.5/4/4.5/5 seconds. Attacking will break the stealth. If Bloodsucc has 10 stacks of Blood he also gains 30% movement speed during the invisibility. However this does not consume the stacks of** Blood**. cooldown: 22/20/18/16/14

E: Umbral Summons Bloodsucc summons a swarm of bats to fly around him for 3 seconds. This deals 30/40/50/60/70+(25% ability power) damage every second. Enemies caught in the area are nearsighted. This ability can be cast during empowered Kiss of Death. area of effect: 250 cooldown: 15/14/13/12/11

R: Kiss of Death Bloodsucc bites a target enemy champion. This causes them to bleed for 150/210/270+21/30/39% enemy's max health (+3% per ability power) damage over the next 3 seconds.

Empowered: Bloodsucc suppresses an enemy for 3 seconds, and drains their blood during this time. This deals 300/450/600+21/30/39% enemy's max health (+6% per 100 ability power). If the enemy is cleansed during this time 50% of the ability's cooldown is refunded. Bloodsucc is healed for 30/40/50% of the damage this deals. Range:200 cooldown: 90/70/50

Pros: Massive single target damage Empowered ult+e is a death sentence

Cons Very low mobility Low Clear speed Rendered ineffective by grouping Countered by cleanses

Please leave any thoughts on the concept, thank you!