Cybermen

The story you remember is probably...

The Five Doctors (1983).

Lured to the Time Lord's Death Zone on Gallifrey, the Cybemen met their match in a Raston Warrior Robot.

"The Most Perfect Killing Machine Ever Devised" ^TM may look like an innocent silver robot in tights, but it made mincemeat of them with its flashing blades.

Find out more in the The Five Doctors episode guide.