Add a “classical mechanic” monster as a counterpart to the quantum mechanic. It has a unique attack strategy; if it’s not in melee, it will rush towards you all at once and send you flying when it collides. This is an elastic collision that conserves momentum, so how far you are sent flying depends on how far it traveled to reach you and your relative masses.

If it is in melee range, it has a melee attack that drains your magic energy to make itself stronger, but if you subsequently kill it and eat its corpse, you regain exactly as much energy as you lost (conservation of energy). They also mutually grudge quantum mechanics.

Chatting to a quantum mechanic can result in them talking to you about physics, causing you to become confused, subject to a roll against your Intelligence (lower being more likely to result in confusion).

Sometimes, eating a quantum mechanic corpse and causing your velocity to become uncertain can give you temporary very fast speed instead of toggling intrinsic speed. (In variants that implement a player-side slow intrinsic, it should also be capable of giving a temporary quantity of that.)

If you have teleport control, quantum mechanics’ attacks toggle your speed instead of giving you a free controlled teleport.

Quantum mechanics’ hits toggle your intrinsic speed instead of teleporting you if you have teleport control. (You already know your position, so your velocity must become uncertain.)