User blog comment:Pacpac1997/Possible New Debuff Kind: Hp Freeze/@comment-4834593-20120619191011/@comment-3450702-20120619200040

yeah, a debuff on an enemy or buff on an ally. It could be the ult of some new support champion, doing this in addition to something else (speed/slow, damage boost/decrease etc., lots of possibilities), for a pretty short duration to prevent brokenness.