- Unlike Voldemort, Acererak always keeps his phylacteries safe; and if brought down to one left; just leaves a dimension to recover instead of gambling it all for revenge.
- Possibly Confirmed. At the end of 'Tomb of Annihilation'', there is no phylactery to find because he keeps it on a different plane. It even says if you win that he'll likely wait elsewhere until old age kills your characters.
WMG / Tomb of Horrors