Mecha Zero Sion
Just like Leona, Sion is not really playable without this skin. Most skins in Sion make it ugly and ineffective, while Mecha Zero Sion turns the flesh of the undead into impenetrable metal. Do you feel like fighting against a giant machine that comes to life again? The answer is no.
Thanks to your steel shell, you'll be less susceptible to damage and control from your opponents. Your "killer smashes" do far more damage and stun longer. Finally, when you use your Ultimate, the sound, which resonates over the rift, casts an aura of widespread fear over the enemy team. Panic then seizes them, while you are launched, the locomotive is unstoppable.
For all Sion lovers who don't yet have this skin, fall for it and become a train of death. That's the best we could come up with, sorry.