Defeat the professor's radscorpion in three challenges is a quest in Fallout 2.
Quick walkthrough
The Chosen One can try to defeat the radscorpion in 3 tests: Perception, Agility and Intelligence. However, after defeating the radscorpion in chess (and only when using the strategy given by the talking plant) it will get angry and try to attack the Chosen One.
Detailed walkthrough
The Chosen One can only win the Intelligence test, a chess game, by learning the "Flying Liver Attack" from Seymour after doing him a favor - digging him out and planting him near old ghouls' home. The other two test the Chosen One's Perception and Agility and can be won by stealing the radscorpion's spectacles or if that's not enough, dosing it with two doses of Jet or Buffout, waiting for negative withdrawal effect to kick in, then taking the according test. Killing the professor's radscorpion is bad for karma (-10), so to avoid that after beating it in chess just run out of line of sight, enter Sneak mode and exit combat, the scorpion won't remain hostile.
