Your first attack against an enemy champion slows them (per unit cooldown). Slowing champions with active items shoots a freeze ray at them, creating a lingering slow zone.
You get free boots at 10 min. but you cannot buy boots before then. These boots give additional MS. For each takedown you acquire the boots 30s sooner.
Gain permanent health when enemy minions or monsters die near you.
Offense
+1-10% CDR
Flex
+6 Armor or 8 MR (match-up)
Defense
+15-90 Health
WhyGlacial Augment
Glacial Augment's slow is great for setting up a well-charged Q or follow-up damage while in passive form after dying.
WhyMagical Footwear
Magical Footwear's raw gold value accelerates your tank items in the mid game so that you become an unkillable machine,.
WhyBiscuit Delivery
Biscuit Delivery's missing health regen synergizes well with Sion's large health pool for massive sustain lane pressure.
WhyApproach Velocity
The extra movement speed from Approach Velocity is great when paired with Glacial Augment, allowing you to chase and stick to targets slowed from autos, [Q], and [E].
WhyConditioning
Conditioning is an incredibly strong scaling rune that can make you a late game monster tank, but if you're playing into a strong early laner take Iron Skin or Mirror Shell instead.
WhyOvergrowth
Overgrowth synergizes incredibly well with Sion's [W] passive allowing you to hit massive health number in the mid to late game.