The grand finale for the DLC!
After the cut-scene, you'll be back in the simulation. Defeat the supergimp and head to the next waypoint. Here, you'll do battle with the dominatrix. Defeat her, but it's not done quite yet.
She'll reboot the system and it'll appear like you're at the beginning of the DLC again. Head down to the lobby or out to the helipad (faster) and you'll confront the witch once more.
Much like the wardens in the main story line, you'll have to use your powers to drop her shield. After you damage her a bit, she'll disintegrate and tanks will spawn. Finish off the tanks. Attack the dominatrix again once she reintegrates. After a short attack, VTOLs will appear; off them.
She'll show up once more, finish her one last time. Once she's defeated the 'cheevo will pop. Congrats!