Solasta: Crown of the Magister
132 Achievements
GOG
Death is only the beginning
Resurrect a fallen character
36.7%
How to unlock the Death is only the beginning achievement in Solasta: Crown of the Magister - Definitive Guide
Easiest way to do this is probably using a revivify spell. Once one of your characters fails all 3 death saving throws, a counter will appear signaling the amount of rounds you have to revive them before they die for good. Simply use the spell within that time and the achievement should pop.