First you need to find a destroyer by interrogating worms and getting captain information. Once you've found one, head to his location and brand him.
Now, you need to die. Either by a captain or grunt, it doesn't really matter. This'll open up an vendetta mission. Once it's spawned go to the Army menu from the pause menu. Find your Destroyer and press
, this will open up the commands. Find the captain that killed you and press
again to confirm and the achievement will unlock.
You can tie this to helping a grunt get promoted to Overlord, sometimes the gane will be a pain in the arse and make him more powerful than you so you can't brand him on vendetta. If a grunt superceed's your level once he kills you, you can make usage of shame to continue on with the next achievement.
Also, if you've completed all Bruz missions and have the "worse than death" skill. This will make the overlord achievement easier.