Grubberfly's Elegy is a Charm in Hollow Knight. When at full Masks, it causes Nail strikes to shoot a projectile which deals 50% Nail damage per hit.[Note 1] Projectiles can pierce enemies infinitely, although they can't do multiple ticks of damage to one enemy.
Usefulness
Grubberfly's Elegy is an effective Nail range upgrade, this Charm is very powerful as a crowd-control tool and when fighting certain bosses such as the Watcher Knights, or Oro and Mato.
This Charm is useful for completing the Delicate Flower quest as it allows for fighting from a distance.
It can be used for exploring areas and switched out for another Charm when fighting bosses. However, during the fight with the Radiance, the projectiles of Grubberfly's Elegy can deal damage to the boss without the need to jump, which can be a viable source of damage when combined with the Quick Slash Charm. This also applies to the Flukemarm fight as the combo makes quick work of her without needing to jump to reach her.
The range of the projectiles is not affected by Longnail nor Mark of Pride, though their height is increased 35% with the latter.
Grubberfly's Elegy can be useful for defeating 
Radiant difficulty bosses since the Charm's effect is never lost, as being hit results in instant death anyway.
When used with Joni's Blessing, taking damage of any kind halts the effects of Grubberfly's Elegy until resting on a Bench, even if the health is restored by Hiveblood.
How to Acquire
Gifted by the Grubfather after freeing all 46 Grubs.
Charm Synergies
 Grubsong |
When used in combination with Grubsong, the amount of SOUL received from taking damage is increased by 10 (to 25 SOUL). |
 Fury of the Fallen |
Fires red projectiles at one Mask, dealing ~67.5% Nail damage per projectile.[Note 2] Note that this works only when the Knight has only 1 Mask left (No projectiles are sent at 1 Mask if Fury of the Fallen is not equipped). While at one Mask, gaining any Lifeblood Masks negates the effect of Grubberfly's Elegy but not the effect of Fury of the Fallen. |
 Mark of Pride |
Increases the height of the projectiles from Grubberfly's Elegy by 35%. |
Charm Combo Tips
 Fragile Strength |
Stacks multiplicatively with Fragile Strength, dealing ~77.5% Nail damage per projectile.[Note 3][Note 4] |
 Lifeblood Heart |
Grubberfly's Elegy only counts Mask health as full health, so by using Lifeblood Masks (except those gained from Joni's Blessing), taking damage no longer removes Grubberfly's Elegy's effect. |
 Lifeblood Core |
Can be used as an alternative to Lifeblood Heart with a higher Notch cost. |
 Hiveblood |
Taking damage and then regenerating it with Hiveblood restores Grubberfly's Elegy's effect. However, this does not work in combination with Joni's Blessing. |
 Quick Slash |
Allows the Knight to launch projectiles at a faster rate. |
 Heavy Blow |
Allows projectiles to knock back enemies from greater distances. |
Notes
- ↑ 1.0 1.1 The damage is rounded to the nearest integer, or nearest even integer if halfway between two. This results in 2/4/6/8/10 damage at Nail upgrades 0/1/2/3/4.
- ↑ First, the damage multiplier from Grubberfly's Elegy (50%) is applied and rounded. Then, the damage multiplier from Fury of the Fallen (150%) is applied and rounded, also to the nearest integer. This results in 3/6/9/12/15 damage at Nail upgrades 0/1/2/3/4.
- ↑ First, the damage multiplier from Fragile/
Unbreakable Strength (150%) is applied and rounded, also to the nearest integer. Then the damage multiplier from Grubberfly's Elegy (50%) is applied and rounded. This results in 4/7/10/13/16 damage at Nail upgrades 0/1/2/3/4.
- ↑ With all three Charms, the damage of Grubberfly's Elegy's projectiles is calculated as follows: First the damage multiplier from Fragile/ Unbreakable Strength (150%) is applied and rounded. Then the damage multiplier from Grubberfly's Elegy (50%) is applied and rounded. Finally, the damage multiplier from Fury of the Fallen (150%) is applied and rounded. This results in 6/10/15/20/24 damage at Nail upgrades 0/1/2/3/4.
