Deep Focus

Deep Focus is a Charm in Hollow Knight. It doubles the Masks healed when using Focus but increases Focus time by 65%.

Usefulness
With Deep Focus, it takes 65% longer to Focus, not including the startup time (0.25 seconds). Startup time is not affected by Deep Focus.

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.