We first need to identify what a superlative form of an adjective is. That is when the adjective is put in a comparison, and is done so in it's higher form. For example, take the adjective "great". The superlative form would be "greatest". That would imply that there are, including the object that the superlative adjective is describing, 3 or more things. So, you use it only when comparing 3 or more nouns.
Ask one of the guards which door would the truth telling guard point to and if you asked the truth guard it would say I would point you to that door and is you asked the liar then it would say the truth telling guard.... hope this is right
