Kryptonite factor

Any given time where there's something (place / substance / object) that draines the whumpee's strength or inflictes them pain or sickness.

The classical example, as the title says, is what kryptonite does to Superman.

Check the complete Tropes index for more.

Animes
Kyou Kara Maou


 * Ep 14: Gwendal von Voltaire and Yuuri are captured, mistaken for running lovers, and are taken to a "trial". But as they are on human territory and next to a mine of all places, the amount of Houryoku (a mineral substance) emanating is painful to Gwendal, who is weakened by it.

Tv Shows
Superman & Lois


 * 1x07: Superman (Tyler Hoechlin), running into a trap by The Stranger, is put under the light of red solar pannels, which drains his strength and makes him defenseless against the man's hammer attacks. He crawls on the ground, unable to get up.
 * 1x08: A soldier helping a prisioner escape prepares an ambush for Superman, using kryptonite gas to weak him from the inside. Superman is weaken enough to remain on the ground, with a kryptonite lance touching his chest, ready to kill him.