one way heroics end-game spoilers if you scroll way down there




























































The End of the World ending tells you, but smack the Darkness with a thrown Holy Weapon or a Holy Spear/Bow, then continue to beat the hell out of it with ranged weapons (> 1 range) until it dies. This'll get you Fairy Ending 3.

I think you can get an ending if you have Viktor alive in your party and then defeat the darkness.
There is another ending if you recruit Sara and then defeat the darkness.

To do that, toss a Buddy Tablet at Sara, then talk to her, then trigger the Darkness fight and hit it once, then talk to Sara again and there should be a new option.

(Sara = a mostly non-spoilery way of saying Demon Lord since 'you can recruit the demon lord' is high-end spoilery tactics and you can't find out who Sara is unless you've already chucked Buddy Tablets at her)