From Fate/Grand Order Wiki
"A Quantum Particle.
A fluctuation in the spiritron that grants many possibilities.
Used as fuel to conduct all sorts of magecraft.
Used to level Servants/CEs/Skills/NPs"
Quantum Piece (QP / クォンタムピース) is a basic currency that is used for a variety of game functions, including leveling Servants and Craft Essences, reinforcing Skills, upgrading Noble Phantasms, and Ascending Servants. They are earned by completing Quests, burning excess cards, or as a common chest drop from most enemies in the game.
The Chaldea Daily Quest Into the Treasure Vault awards significant amounts of QP. Most Events also have a way to obtain large quantities of QP, as part of the event activities and/or as an exchange for event items.
- On August 31, 2015, the following changes were made to QP drop rates (JP):
- QP drops from Main/Free Quest monsters increased by 10x
- QP from clearing Main/Free Quests increased by 10x
- QP drops from Daily Quest monsters increased by 5x
- Large QP chest drop rate increased by 2x.