Stockman should have used other D words than Doom.
I get that this is probably typical of a wimpy, hapless guy like him. To not be able to think of any other words other than Doom for his trap.
But honestly, he should have probably many other different words starting with "D".
Like, still the maze of "Doom".
But he also could have said "Bonus Round of Destiny", "Staircase of Dynasty", "Maces of Danger", "Monster of Destruction", "Final Round of Demise", etc.