Hand of Reckoning is a spell. It can't be cast when silenced, but based off testing on Growl and Dark Command, no longer suffers from miss chance when cast by a level 80 vs a boss-quality mob. Prior to Patch 4.0.1, it had a 17% chance to miss raid bosses (in contrast to the 8% chance to miss boss mobs for melee attacks). Prior to Patch 4.0.1, even if you were melee hit-capped (263 hit rating at level 80), Hand of Reckoning's chance to miss was still 7.0%. This gap was covered with Glyph of Righteous Defense (removed in Patch 4.0.1).