Force multiplier
The user can multiply anyone's stats up to 10,000 times fold to increase their overall force. They can do this by behaving similarly to an enzyme and lowering the energy of activation (the energy required to start a reaction or process) so the target can use their quirk in the most efficient way possible in addition to simultaneously channelling a part of their energy into the receiver's body to further potentiate their abilities.
However, to do this the user must be in physical contact with the target though not necessary skin to skin contact or be within a 20 meter radius of them. The multiplying effect applies to the receiver's quirk power, their physical strength, stamina/vitality, speed, agility, and other skills except intelligence which remains unaffected. To multiply someone's abilities easier, the user can shrink themselves down up to the size of a marble which is perfect for being carried around and going undetected by the enemy.
Nevertheless, the multiplying effect does put considerable stress on the receiver's body so the limit to how much power can be utilized and the length of usage time depends on the physical fitness of the target (so they can't be too injured or sick). In addition, the user's own body and health must be at their best otherwise it will decrease their quirk's effect.
As a way for the user to replenish their own vitality, they can take the energy from living organisms (can kill accidentally when doing this if not careful), from other external sources such as: solar, heat, and electrical energies, and by eating proper meals (not depending on unhealthy snacks) or sleeping. The two latter options yield the best results as they allow the user's own body to replenish its strength and to rest adequately though due to their quirk, they will need 10 hours of sleep vs the usual 8.
(Yes, a viable excuse to sleep more! I could do with that.)
Force multiplier makes the user one of the best supportive figures in a team battle. Though since it lacks firepower, they won't be able to directly fight on on one with enemies. They can however use their quirk's 20 meter radius reach to fight from a distance. The user can abnormally increase an enemy's abilities/quirk to throw them off their game and to also put a stress on their bodies. This is because suddenly multiplying an enemy's power can make them lose control of their quirk, can increase the onset time of their quirk's drawback effects, and they can make the target accidentally friendly fire due to being unable to modulate their newfound strength.
Nonetheless, this can be a double edged sword because if the user encounters someone with the ability to quickly adapt, then they would be making their opponent into a power house temporarily as they can cancel their multiplying ability to return the enemy to their original strength.
Drawbacks: exhaustion, somnolence (can fall in a deep sleep easily like a narcoleptic if they don't rest enough), and joint/muscle pain from shrinking down for long periods of time.