The Celestial Toymaker

DODO: We'll never see him again, will we, Doctor?

DOCTOR: Oh, my dear, don't talk too soon. The mind is indestructible. So is the Toymaker.

STEVEN: What, you mean he can never be destroyed?

DODO: But you defeated him.

DOCTOR: Yes, just at this moment, but there will be other meetings in another time.

DODO: Then your battle with him will never end.

DOCTOR: Yes, you're quite right, my dear, but anyway, let us cheer up. After all we did win the games.

TOYMAKER: Make your last move, Doctor. Make your move.

DOCTOR: But if I do, this place vanishes.

TOYMAKER: And then you have won completely.

DOCTOR: And if this place vanishes, then the TARDIS and the rest of us, will vanish also.

TOYMAKER: Correct. That is the price of success. Make your last move, Doctor. Make your last move.

DODO: Who's the Celestial Toymaker?

DOCTOR: He's a power for evil. He manipulates people and makes them into his playthings. Whatever you do, neither of you must look at that screen. It's a trap.