After defeating Sifa Grent, Dack acquired another problem by stealing a gauntlet from the Boros on Ravnica. The artifact was incomplete. Its missing part carried his search to Theros, making the latest prize a reason to cross another boundary rather than a secure conclusion.
He eventually assembled the gauntlet after reaching a mysterious Theros island. Ashiok's manipulation of a polis through dreams then interrupted his investigation. Being able to understand a magical object did not place Dack outside the reach of magic aimed at the people around it.
Dack entered the Underworld seeking help. He was still alive: this journey does not establish a later resurrection or make the gauntlet an escape from death.