Think they have this on Riot's forums somewhere..
Example:
Jinx Super Mega Deaths Rocket!
RANGE: Global
COST: 80 MANA
COOLDOWN: 60 / 50 / 55
MINIMUM PHYSICAL DAMAGE: 200 / 250 / 320 (+ 50% bonus AD)
MAXIMUM PHYSICAL DAMAGE: 320 / 400 / 520 (+ 100% bonus AD)
ADDITIONAL DAMAGE: 25 / 30 / 35% of enemies' missing health
Example:
Jinx Super Mega Deaths Rocket!
RANGE: Global
COST: 80 MANA
COOLDOWN: 60 / 50 / 55
MINIMUM PHYSICAL DAMAGE: 200 / 250 / 320 (+ 50% bonus AD)
MAXIMUM PHYSICAL DAMAGE: 320 / 400 / 520 (+ 100% bonus AD)
ADDITIONAL DAMAGE: 25 / 30 / 35% of enemies' missing health