This is the tomb of Rassilon, where Rassilon lies in eternal sleep. Anyone who has got this far has passed a number of dangers and has showed great courage and determination. To lose is to win and he who wins shall lose. Anyone who takes the ring from Rassilon’s hand and puts it on shall get the reward he seeks.
What reward? Answer - immortality.
The first Doctor then tells the Master – you’re hardly a suitable candidate
Rassilon knew that immortality was a curse and not a blessing.
Note: this is from “The Five Doctors.” The Timelords in their early days brought candidates to the death zone where they would fight to get to Rassilon’s tomb to receive their reward. Has Richard’s immortality been a blessing to him? Don’t even know if this even fits in the story at all. Just started thinking about Rassilon’s tomb.