Instead of adding a whole villian factor to Garen, add this.
Garen should, instead of having a villian thing, and true damage, (which is blatantly insane), how about, making Garen deal increased damage to the enemy who has had something to do with the most recent kill? Think about it, as a crime case.
has molested killed
- molsteors that assisted are,

.
Garen will deal increased damage, instead of true damage, which is blatantly insane, so that way, Garen has more choices to use his ultimate on, and not focused on one person. Plus, you should never let ANYONE, deal true damage that easily, unless it's Darius, because Darius, well... he likes to dunk.
BUT STILL. This suggestion is so much better to be honest, because now all the pedophiles I mean, enemies are all gone! "god dammit... why do i keep having pedophiles in my threads.."
I mean... But seriously though, having increased damage for assists, is so much more fair. (A cooler effect could be, Garen will deal more damage depending on how did the most damage, and the least damage to the enemies who had the least to do with it. Because, logically, Garen wants to kill the people who did the most damage to his teammates right?