Zectronic beam

A Zectronic Energy Beam was a powerful thing that could conquer the universe 'in minutes' according to the Ninth Doctor. When pressed about how this was to be achieved by his companion Emma, he said 'I'll explain later'.

Zectronic Energy was capable of destroying the regenerative process of a Time Lord, but nonetheless the Twelfth Doctor regenerated into the female Thirteenth Doctor. (DW: The Curse of Fatal Death)