Shadow of Vanish Grab
From Diablo Wiki
Shadow of Vanish Grab is a spell that may be used by Diablo or by the Shadow of Diablo once you are trapped as a consequence of the Hell Spike spell. When Shadow of Vanish Grab is used you end up in Diablo's claws where you continuously burn for the duration of the spell. There is a little icon above the "Achievements" icon in the menu bar that appears while under the influence of this spell. Hovering over this icon tells you how many seconds are left before the spell terminates.