Active: Skarner rears his stinger, rooting his target for 0.25 seconds as he brings his stinger down, dealing magic damage and suppressing it for 1.75 seconds. At the end of the suppression, the target takes the same damage again.
If Impale's suppression is removed via a method of crowd control removal such as Quicksilver, the secondary damage is not dealt.
If Skarner loses sight of his target or if his target exceeds a range threshold during the initial 0.25 seconds, the ability is cancelled but does not go on cooldown.
Impale's target can exceed the threshold either by being in the process of dashing when immobilized, removing the immobilize and then quickly moving away, or by an ally knocking Skarner back.
Skarner's target will follow him around regardless of the method of movement - including through forced movement spells such as Buster Shot and Dark Passage.
While Impale's suppress is active, Skarner is considered to be facing in the direction of his movement, not the direction he is facing, for the purposes of abilities such as Petrifying Gaze and Mocking Shout.