Passive: When auto-attacking the same target for 4 seconds, Sion snares the enemy for 1.0 / 1.25 / 1.50 / 1.75 / 2.0 seconds; Sion cannot snare the same target within 6 seconds.
Active: Sion dashes to a single target enemy dealing physical damage. Any enemies that are in the way of the target enemy are pushed briefly aside, but are dealt no damage. Additionally, Sion reduces the armor/mr of the enemy for 4 seconds.
Active: Sion surrounds himself with a shield which absorbs incoming damage and gains a movement speed buff of 10%, which becomes 15% when an enemy has their back turned for up to 10 seconds. The slow decays by 5% after 5 seconds. After 5 seconds, if the shield is not broken, Sion can detonate the shield but costing him health, dealing physical / magic damage to nearby enemies. If Sion does not detonate the shield after 10 seconds, the shield explodes automatically but Sion does not lose health. Additionally, enemies that are 300 units closer to Sion's explosion radius take 20% more damage.
Active: Sion swings his axe recklessly making his next basic attack deals bonus damage and causes the enemy to bleed for 5 seconds. If the enemy dies, Sion regenerates 0.8% of his maximum health for the next 7 seconds.
Passive: Sion gains 1.0/1.5/2.0 (upgrades at levels 1/7/13) fury per second. Using abilities, Sion gains 5 fury instead, and auto attacks bring 3 fury.(max 100)
Active: For the next 10 / 15 / 20 seconds, Sion gains bonus attack speed, a attack damage buff, and bonus lifesteal. Sion's range is increased by 50 (175). During this time, Sion's auto attacks do not bring fury, but Sion still passively gains fury. Additionally, Sion's basic attacks will heal surrounding allies for a percentage of the damage dealt.
After reading comments about changing his ult, I decided to make a direction number 2 of his ult.
Fury of the ancients
COST: 100 FURY
Passive: Sion gains 1.0/1.5/2.0 (upgrades at levels 1/7/13) fury per second. Using abilities, Sion gains 5 fury instead, and auto attacks bring 3 fury.(max 100) The ult is only available when Sion reaches 100 fury.
Active: Sion lets out a battle cry of the ancients, dealing physical and magic damage to all nearby enemies, healing Sion for a percentage of the damage dealt. If Sion hits more than one enemy, Sion reduces enemy spells and basic attacks by 30 / 40 / 50% and Sion's range is increased by 50, (175) and his auto attacks do magic damage for 10 seconds. (It's not like karthus's E, more like Rengar's W. Also, the magic damage does NOT affect structures.)