Grubsong

Description
Contains the gratitude of freed grubs.

Gain SOUL when taking damage.

How to Acquire
Gifted by the Grubfather when the player has freed 10 Grubs.

Usefulness
This is perhaps the best charm available with a one-slot cost, as it provides ample SOUL for healing whenever you get hit (i.e., when you need it). The SOUL provided per hit is not enough for a heal on its own, but in conjunction with the SOUL you gather by striking enemies, especially with Soul Catcher, you should be able to sustain yourself pretty easily.

It also shines in difficult platforming areas where enemies are not readily available for healing. It combines well with charms like Hiveblood and Deep Focus to keep the Hollow Knight nearly invincible outside of boss battles.