Die for the first time
Reach the end of the 3rd act for the first time
Unlock Vier
Unlock Nau
Unlock Dix.
Reach the end of the game for the first time.
Hit an enemy's weakness!
Have over 25 stacks of decay on an enemy at once.
Unlock the key to the end
Clear Danger Level 1.
Cast the ultimate spell.
Cast the Doom Spell.
Manipulate the laws of time.