"Don't bother trying to regenerate. You got the full blast. You see, Missy, this is where we've always been going. This is our perfect ending. We shoot ourselves in the back."

The Master's laser screwdriver was intended to be larger and more intimidating than The Doctor's sonic screwdriver. This, as well as its lethal and dangerous settings, fit in line with The Master's portrayal as an antithesis of The Doctor.

After Missy stabbed him in the back and left him to regenerate in an elevator, The Master (refusing to allow his future self to help The Doctor) blasted her in the back with his laser screwdriver. The Master told Missy that she could not regenerate as he gave her the full strike on maximum power, leaving her to die as he departed.

Designed by Peter McKinstry and built by Nick Robatto, this is one of only two hero prop laser screwdrivers ever created for filming on Doctor Who. The first hero prop was built for the laser screwdriver's first appearance in the Series Three finale, “The Sound Of Drums”/"The Last Of The Timelords" alongside an additional full set of backup parts. 

The backup parts were assembled later to create an additional hero prop ultimately hired out for filming on the Series Ten, Episode 12, "The Doctor Falls".