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