After being killed, Sion will reanimate with rapidly decaying Health. His attacks become very rapid, gain 100% Lifesteal and deal bonus damage equal to 10% of his target's maximum Health (max 75 to monsters).
All his abilities are replaced with Death Surge, which grants a burst of Movement Speed.
Q - Decimating Smash
Sion charges a powerful swing in an area in front of himself that will deal damage to enemies when released. If he charges for enough time, enemies hit by the swing will also be knocked up and stunned.
W - Soul Furnace
Sion shields himself and can reactivate after 3 seconds to deal Magic Damage to enemies nearby. When Sion kills enemies, he passively gains maximum Health.
E - Roar of the Slayer
Sion fires a short range shockwave that damages and slows and reduces the Armor of the first enemy hit. If the shockwave hits a minion or monster, it will be knocked back, damaging and slowing all enemies that it passes through.
R - Unstoppable Onslaught
Sion charges in a direction, ramping up speed over time. He can steer his charge slightly with the mouse cursor location. When he collides with an enemy he deals damage and knocks them up based on the distance he has charged.