Traditional Sion

Two reasons for this:

1. The Champion Update team (ChampUp) believes they got the intentional feel of Sion with his rework, something they admit they missed with Karma, Trundle and Sejuani after their reworks. Sion is supposed to be this badass, undead juggernaut (b****), not some half-mage, half-fighter mess of a kit with a silly Arnold-inspired voice.

2. The Arnie voice wasn't enough of an incentive, internationally, to create a special skin with its own unique voice. The fun Arnie-voiced experience was limited only to English-speaking fans, which are outnumbered by the rest of the world.

I don't necessarily agree with these reasons, but they are what they are.