8-10 hours or something.
Not to be a party spoiler or anything, but HeC was the first arti I got for my healer. Now its sitting nicely in my vault and has been for quite a while. Stats aren't very good, and never used its abilities. If it was me I'd look for a high utility cloak like Feathered Wrap or Otrygg's Darkened Cloak. Either that or the elusive Cloudsong.