Renekton and Darius

Renekton and Darius fill the same kinda role in lane, bullies. I like to think they are both ment to gain an upper hand in lane and snowball. Renekton recently got a tweak helping him scale a little better later in the game, but I've yet to even SEE Darius in any patch notes for the longest time. I feel that is worse off than what with his mana pool, resetting ult that takes quite a bit of mana to fire off, no built in sustain, no mobility which then makes him an easy gank target and to cap it all off he falls off like a cement truck off a cliff no matter how fed you are if they aren't bad. Renekton can just jump through the frontline to the squshies and blow them up if he isn't peeled off. While Darius is forced to just run at them and hope that not only is the peel bad, but that the carries are bad at kiting as well! Some people (if they are good enough) just forget about catching them if you don't have flash! Why is it okay for someone with the same role (and an unlimited resource) allowed to get love and tweaks while Darius is forced to pray on baddies just to be "Okay".

Edit: When Blink Dagger?