Legate Danig Kell was a Cardassian military officer, who served in the Cardassian Central Command. He was Skrain Dukat's commanding officer aboard the starship Kornaire and then during the occupation of Bajor.
Dukat didn’t find out about the modification until 2371, when it was accidentally activated by the new inhabitants.
In a taped message to Dukat, that would activate when the secret subroutine activated, he said:
Dukat... If you're seeing this recording, it means you tried to abandon your post while the station's self-destruct sequence was engaged. That will not be permitted. You have lost control of Terok Nor, disgracing yourself and Cardassia. Your attempt to escape is no doubt a final act of cowardice. All fail-safes have been eliminated. Your personal access codes have been rescinded. The destruct sequence can no longer be halted. All you can do now is contemplate the depth of your disgrace. And try to die like a Cardassian.