Here is the full list of all 15 Xanadu Next achievements.
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.
Barely made it back to shore after almost drowning.
Found and translated all tabulae and memoirs.
Mapped 100% of the game.
Reached max rank.
Defeated Berilard.
Defeated Dvorak.
Defeated Scoltula.
Conquered another dimension.
Attained all other achievements.