Sion was rebuilt in a major way. His new build makes him a very flexible champ and his new skills make him an AD support for serious change up to the meta. As a support, Sion can put some serious poke damage and slows on the enemy bot team. He is tanky in nature to start with and you build to that strength. Focus your E skill for the poke & slow and the Q to stun when being offensive. When being defensive, the E can be used to keep the enemy at range to avoid you and use the Q to stun anyone going after your ADC. Use your shield when they switch off the ADC to deal with your annoying self and you retreat to safety with the shield absorb. I'll develop this guide further as the new Sion and the idea of support is played out further. So far, it gives you a great aggressive support with a serious team fight late game dynamic non-typical to supports.