Hollow Knight (UP)
35 Achievements
57-69h
Nightmare's End
Complete the tale of the Grimm Troupe Details for this achievement will be revealed once unlocked
7.2%
How to unlock the Nightmare's End achievement in Hollow Knight - Definitive Guide
The Grimm Troupe DLC is not over yet, as Grimm asks you to gather yet more flames across Hallownest. In Deepnest, one of his subordinates will ask you to help him banish the Grimm Troupe and to go back to the cave in Howling Cliffs to do it. You can choose to banish them or follow Grimm's instructions. Either way, the trophy will be yours. I would recommend doing Grimm's instructions, as the next boss fight will appear in the Pantheons and you can use this to get some practice in beforehand; plus the Charm Grimm's subordinate gives you, Carefree Melody, pales in comparison to the complete Grimmchild you get. When you've gathered the flames and return to Grimm with the Grimmchild, you will see him cocooned in the back. Use Dream Nail on him and you will enter a battle with Nightmare King Grimm.
Grimm is now much stronger in this form, his attacks deal two masks of damage, his attacks are faster and fiercer and has a new move. He no longer bows before the start of the fight. The swipe, uppercut, fireball attack now rains more fireballs, making it harder to avoid. The double dive attack now has a flame trail, making it impossible to jump over him, making you have to jump above or in front of him. He now launches four fire bats instead of three. His ground spike attacks happen much faster and he no longer appears on the ground to do it. His puffed up fireball attacks are fired at a much faster rate. His new attack has him float in the middle of the room and fire pillars appear where you stand. He is vulnerable in this state but you must be careful of the fire pillars cornering you. Use Shade Cloak to avoid them if they overwhelm you. He will still recoil when you get too close before an attack and transform into bats when you deal enough damage. You will most likely die a few times in this battle, but the best thing to do is get used to his attack patterns and do your best to dodge them as much as you can. Don't get greedy with attacks, because Grimm will punish you for it. Do your best and after you hit him enough times, he will be defeated, his Grimm Troupe tents will vanish, save for Divine's tent if you haven't spoken to Leg Eater after acquiring all the Unbreakable Charms and the trophy will be yours.
PS My tip is no longer relevant, apparently it was just a bug and now the achievement is given in any case.