Foreshadowing: Rainsford is locked in his room high up in a tower. What future event do these circumstances hint at ? What hints would force Rainsford into a contest?

This foreshadows Rainsford's final confrontation with Zaroff, in which he beats the hunter at his own game. Rainsford has already been force into a contest... I'm not sure what you mean by the second part of your question.