Charms

Charms are a special type of item in Hollow Knight that give various bonuses to the Knight. Charms use Notches when equipped and can only be equipped and unequipped while sitting on a bench.

There are a total of 45 Charms, though only a max of 40 can be kept at one time, as 5 Charms are able to be replaced with different ones throughout the game (Fragile Greed for Unbreakable Greed, Fragile Heart for  Unbreakable Heart, Fragile Strength for  Unbreakable Strength, Kingsoul for Void Heart, and  Grimmchild for  Carefree Melody).

Notches
Charm Notches are required to equip Charms. Different charms require a different amount of notches. The Knight starts with 3 Notches. 8 more can be found throughout the game.

Picking up a Charm Notch will heal the Knight up to full HP.

Overcharmed
If the Knight tries to equip a charm that takes more notches to equip than they have, it will eventually be equipped after 5 tries. However, the Knight will become Overcharmed. While in this state, the health bar will have a purple aura and the Knight will take twice as much damage from all sources. To remove the effect, simply remove the charm that broke the notch limit. Subsequent attempts to Overcharm will immediately equip the Charm and cause the effect instead of requiring 5 attempts.

It should be noted that this cannot be performed if the Knight has used all Notches (for example: If the Knight has 3 available notches and have Gathering Swarm + Stalwart Shell, 3/3 is used and no additional charm may be equipped), and only one charm can be equipped past the notch limit. As such, if the Knight wishes to play while Overcharmed, it is advantageous to equip a high-notch charm in the final slot, as the amount of notches over the limit does not affect the Overcharm penalty.

Being Overcharmed is very advantageous for Radiant fights in the Hall of Gods as when taking an infinite amount of damage there is no drawback to doubling what is already a one-hit defeat.

Achievements
Charmes Амулеты 护符 Amuletos Талисмани Amuletos Amuleti Talismane