Rex the Vengeful Lizard

Roles: Fighter, Support Passive: Every time Rex kills a neutral monster, gain 1 stack. each stack gives 2 attack damage. Q: Spine Shell: generates a shield equal to half your armor. this shield decays over 5/7/9/11/13 seconds, during this time, reflect 4/8/12/16/20% of damage dealt to Rex back at the attacker. Cost: 30/35/40/45/50. Cool-down: 30/28/26/24/22 W: Vengeful Grab: steals a colored buff from target champion, lasts 48/96/144/192/240. Cost: 20/22/24/26/28. Cool-down: 50/40/30/20/10 E: Detonation: AoE dealing damage equal to AP. red buff deals damage to health, blue buff deals damage to mana, purple buff deals damage to both. if multiple buffs present, damage overlaps. Cost: 40/45/50/60/70. Cool-down: 30 R: Sign of Thanks: shares all buffs on Rex with all allied champions, subtracting 80/60/40% from the duration. Cost: 100/150/200. Cool-down: 60/90/120

Lore: Once a monster serving in the league, he was fired and replaced. in his anger he trained himself hard and long, until he was acknowledged by the league, becoming a champion. despite his achievements, he has never forgotten the shame he faced. Vengeance will be his.

Feel free to give suggestions, just liked the idea, and uses some interesting mechanics without being seriously broken, thanks.