Failed Champion

"A maggot driven mad by a strange force. Inhabits a stolen armoured shell. Weak creatures love to steal the strength of others. Their lives are brief and fearful, and they yearn to have the power to dominate those who have dominated them."

The Failed Champion is a hidden boss in Hollow Knight. It is the Dream variant of the False Knight, faster and tougher than its physical counterpart.

Behaviour and Tactics
Failed Champion's behaviour is very similar to False Knight's, but his attack rate and speed have been increased immensely. Contact damage/physical attacks now deal two masks of damage, damage from shockwaves and falling rocks still deal one mask. In addition, the following attacks have had tweaks:
 * Leap: Failed Champion only uses this attack after the first stagger/phase. This makes Leaping Bludgeon much more common.
 * Slam: The slam is much faster, and the shockwave created from the slam is much larger and taller. Rocks fall for this attack for all phases.
 * Leaping Bludgeon: The height of the jump is lower. Rocks fall for this attack for all phases.

Since Failed Champion does not give SOUL it is advised to keep the Maggots near his body alive as to Dream Nail them for SOUL to start the fight with. (This tactic does not work in Godhome.)

Failed Champion's jumps are quick, though it is better to dash underneath him when he jumps so as not to get caught by the mace swing. This is made more effective with Shade Cloak and Sharp Shadow (for the increased shadow dash distance) because Failed Champion is so large.

Using Dreamshield can sometimes block the falling rocks caused by most attacks.

It is possible to stay inside a stagger for as long as needed by hitting the armour during a stagger. This resets the stagger timer without damaging the maggot, which gives enough time for a Dream Nail hit or a Focus, especially if Dream Wielder and Quick Focus are equipped. Repeating this for long enough allows fully restoring health every stagger. Note that Failed Champion's stagger should end by hurting the maggot and not by him getting up on his own, as otherwise, that stagger does not count for progressing the fight. (Please see the Pantheon of the Knight video guide for a visual example of this tactic.)

Desolate Dive/Descending Dark is a great Spell to use throughout the fight because of its invincibility frames and damage. Vengeful Spirit/Shade Soul is also useful. It is a good tactic to use Howling Wraiths/Abyss Shriek when Failed Champion leaps overhead and and winds up for a Rage. All spells are made more damaging by the Charm, Shaman Stone.

The Nail Arts Dash Slash and Great Slash are good options for damaging Failed Champion in between attacks.

A very safe strategy is to sit on the left or right wall while charging Crystal Dash far up enough that the False Knight/Failed Champion cannot reach the Knight, but not far up enough that the Knight does not appear on screen (this may cause problems for the following Charm setup). This allows The Knight to avoid all contact with the boss, and instead only have to worry about the falling rocks (which only deal 1 Mask of damage). Dealing damage while sitting in the corner requires some form of a companion- the selection being Grimmchild,  Weaversong, and/or Glowing Womb and Grubsong for its synergy with Weaversong (and keeping Glowing Womb fueled with Soul. Granted, this tactic takes a long period of time to pull off, as the companions do not deal a lot of damage. Additional Charms for this strategy can include  Dreamshield to block the rocks and Sprintmaster to increase Weaverlings speed, range, and damage. Eventually though, Weaversong's spiders might stop spawning. If this happens, it is recommended to use Desolate Dive or Descending Dark since this causes the Failed Champion to jump backwards, giving enough time to climb back up.

Location
Returning to False Knight's arena shows that his body has been moved. To find Failed Champion, there is a breakable wall just above where his arena was, where two Maggots can be found mourning over False Knight's dead body. Using the Dream Nail on the body grants entrance to the Failed Champion fight.

Achievements
References

Campione Decaduto Upadły Czempion Champion Raté