While Gabe Aul announced that the Lumia Icon is now supported for the latest Insider Preview builds, the Verizon-exclusive device is also supported for the Slow ring, with build 14295.1005.
Build 14295.1005 RSS
Microsoft has released Windows 10 Insider Preview build 14295.1005 for both PCs and phones on the Slow ring. While it's the second cumulative update for PCs running 14295, it's the first for phones.