Talk:Iceborn Gauntlet/@comment-5.83.71.124-20121221214254/@comment-68.109.110.108-20121223061155

It isn't.

"Slow effects derived from items' passives do NOT stack, even when coming from different champions. Only the strongest item slow is applied at any moment. The exception to this is the active effect of Randuin's Omen,  Hextech Gunblade and  Bilgewater Cutlass, which stacks with other slowing items normally because they are considered champion abilities for slow stacking purposes."

http://leagueoflegends.wikia.com/wiki/Movement_speed

I edited the article appropriately.