Here is the full list of all 15 Xanadu Next achievements.
Mapped 100% of the game.
Reached max rank.
Attained all other achievements.
Found and translated all tabulae and memoirs.
Conquered another dimension.
Defeated Galsis.
Innately learned all skills and acquired all levels of all spells.
Found and maxed out all Guardians.
Defeated Lorelei.
Defeated Ascomoid.
Defeated Evilwurm.
Defeated Scoltula.
Defeated Dvorak.
Defeated Berilard.
Barely made it back to shore after almost drowning.