Deep Focus is a Charm in Hollow Knight. It doubles the masks healed when using Focus but decreases Focus speed by 65%.
Usefulness
Its restrictive cost and slow focus time make it hard to use in boss battles. It is better used in areas where there is lots of time to rest, such as while tackling difficult platforming challenges, where it shines in combination with Grubsong and Hiveblood.
How to Acquire
Found in Crystal Peak in a hidden cave made entirely of crystals.
Below the area where Cornifer can be found, look for a Husk Miner mining a wall. Break the wall to reveal the secret area. Requires Crystal Heart.
Charm Interactions
 | Stalwart Shell Useful for guaranteeing a heal when enemies are attacking frequently. |
 | Quick Focus Despite costing a prohibitive 7 notches combined, Quick Focus partially cancels the focus-speed penalty of Deep Focus, allowing the Knight to heal two masks at almost the regular speed. Especially useful against swarms of enemies or enemies who deal two masks of damage per hit. |
 | Hiveblood Combined with Hiveblood, it greatly helps tackling difficult platforming challenges, especially the White Palace. |
 | Grubsong Combined with Grubsong, it greatly helps tackling difficult platforming challenges, especially the White Palace. |
 | Spore Shroom Increases the spore cloud radius by 35%. |
