Omen, the Shadow Stalker

Omen, the Shadow Stalker Primary Role: Assassin Secondary Role: Fighter Secondary Bar: Mana

[Stats] Health: 510-2040 (510 + (85 x level)) Health Regen: 6.125-17.75 (6.125 + (~0.64583 x level) Mana: 325-1250 (325 + (~51.38889 x level) Mana Regen: 6-22.2 (6 + (0.9 x level) Range: 125 (Melee) Attack Damage: 55-125 (55 + (~3.88889 x level) Attack Speed: 0.655-0.855 (0.655 + (~0.01111 x level) Armor: 23-82 (23 + (~3.27778 x level) Magic Resist: 30-52.5 (30 + (1.25 x level) Movement Speed: 350

[Abilities]

[Passive] Mark Of The Shadow Stalker - Marks an enemy with "Mark Of The Shadow Stalker", summoning dark energy on his next attack after "Cover of Shadows" or after 2 basic attacks on a target within 1.5 seconds, altering the effect of the next ability to hit the marked target, The target will stay marked for up to 5 seconds (Dealing damage can extend "Mark Of The Shadow Stalker" for up to 3 seconds).

[Q] Cooldown: 20/18/16/14/12 Mana Cost: 60 (All Ranks) Cover of Shadows - Omen stealth's for 1.5 seconds re-casting the ability within 2 seconds will allow Omen to dash (600 Units) through enemies applying "Mark Of The Shadow Stalker" to them and dealing ((45/60/75/90/105) + 35% Total Attack Damage + 40% Ability Power) physical damage.

(Marked Target) Cover of Shadows - If casted on a marked target "Cover of Shadows" can be re-casted for the ability to dash through the target for (105 + 50% Total Attack Damage).

[W] Cooldown: 11/10/9/8/7 Mana Cost: 40/50/60/70/80 (Scaling With Ability Level) Razor Quills - Shoots in the target direction with a cone of quills (400 Units) from Omen's back crippling, and slowing the enemies hit for (30%/35%/40%/45%/50%) (Scaling With Ability Level) for 2 seconds and dealing ((35/60/85/110/135) + 20% Additional Attack Damage + 30% Ability Power) in magical damage.

(Marked Target) Razor Quills - Applies a slow to the target for 50-90% based on the targets missing health Dealing ((45/70/95/120/145) + 30% Additional Attack Damage + 35% Ability Power) in magical damage.

[E] Cooldown: 12/11/10/9/8 Mana Cost: 40/60/80/100/120 (Scaling With Ability Level) Stalkers Leap - Omen leaps (550 Units) to a small targeted area dealing ((80/110/140/170/200) + 60% Additional Attack Damage) (Scaling With Ability Level) + 15% of the targets current health in physical damage.

(Marked Target) Stalkers Leap - If Omen lands on a marked target, consuming the mark, and dealing ((100/150/200/250/300) + 70% Additional Attack Damage) (Scaling With Ability Level) + 15% of the targets max health.

[R] Cooldown: 120/100/80 Mana Cost: 150 (All Ranks) Shadow Assault - Omen jumps on his target (200 Units) and mauls them for massive damage dealing ((250/350/450) + 0.75% Additional Attack Damage) physical damage.

(Marked Target) Shadow Assault - Omen consumes the mark and stuns the target for 1 second dealing ((300/400/500) + 0.75% Additional Attack Damage) physical damage.

I am looking for feedback ideally from Riot Games staff but all help with any suggestions on how to improve this champion no matter who it may be from is greatly appreciated.