One GitM suggestion, and One suggestion only...

Make Phantoms appear in the stages if the players take too long on a certain segment.
On average, I'd say a 4 person group on either stage takes anywhere from 10-15 (maybe 20?) minutes to complete it. But many people feel like by simply 'taking your time' you can overcome many of the obstacles here without much of a sweat.
The solution? Punish the lollygaggers - after a certain amount of time, or once a 'time limit' threshold is passed, Phantoms spawn and persist through to the end of the stage. It doesn't have to be low enough that it forces players into a speedrun, but *just* low enough that if you're definitely taking your time, you're going to pay for it in the end.
I guarantee you no one wants to have them following behind right in time for the boss.... better hurry~

roffles
This will do nothing.
This would only result in said players attacking an extra five minutes in total to ward off Phantoms.

Sure, it'll do nothing....
...until they come back to life in the middle of your Arena fight against the Shock-Bombie horde room.
Have fun with that.
(Horse knows exactly what I should say)
I fully endorse Phantoms to be included into the final cut of this danger mission.
I will personal make a $20 purchase if they can be shock phantoms.
This is not a bribe or a joke, this is a business.
Please add Phantoms (shock or otherwise) to this mission.