Luke, The Steel Fletched

I have not really thought up lore or base stats for this Marksman champ concept but I would like to hear see other people's thoughts and input on this. I envisioned him to be a repeating crossbow user that is intended for kiting or pursuing.

Passive: Retaliatory Bolts Whenever Luke is attacked by an enemy champion, that player becomes marked for 6 seconds. Attacking that champion grants a flat 10 movement speed buff that lasts for 3 seconds and stacks up to 3 times. Only one enemy champion can be marked at a time.

Q: Piercing Bolt Luke fires a straight line shot that hits the first target in its path. If the hit kills the target the bolt will continue travel till it reaches max distance or hits a second target. The second target takes 150% damage. The bolt is only capable of hitting two targets.

W: Single Out Passive: Attacking a target consecutive times applies a stacking mark that stacks up to three times increasing damage dealt to that target by 20%. Attacking a different target resets stacks. Active: Luke gains increased attack range and the cap on marks on a target increases to 5 stacks for 6 seconds.

E: Hammershot Luke fires a heavy shot at the target breaking their defenses and marking them for 5 seconds. Allies who attack the target deal 8% more damage while the mark persists.

R: Loaded for Bear After a .5 second channel Luke jumps into the air and fires a wide conical attack that deals significantly more damage to targets closer to him than those further away. Targets that are within melee range take 450% damage while targets further away take only 150% damage. The damage is not reduced for targets hit but only for distance traveled. Minions take a flat 300% damage from the ability.

I hope to see some feedback on my idea here and maybe see it come to reality in game someday. As a person who loves the Marksman role, it would be awesome to have made one :)