With the new lock boxes especially a new set of very rare doffs are introduced. I think they are very effective in pvp, especially for cruiser captains (expect to see lot more cruisers in pvp). When facing cruiser premades, it means losing.
So far I noticed the following doffs (purple):
System engineer: +200 resistance to weapons subsystem energy drain for 8 seconds when activating directed energy modulation
Warp theorist: 25% chance of disabling 1 subsystem for 5 sec on enemy targetted by energy syphon
Warp core engineer: Reduces incoming damage to shields by 20% for 30 seconds when extend shields is active
Entertainer: On activation of beams or cannons 1% chance of reducing enemy perception distance by 20% for 6 seconds
I see already 5 cruisers using FAW with DEM while the entertainer (performing striptease in front of the window) reduces perception of all enemy ships. That would be a 5-in-1 ship kill.