The level Keys is impossible to complete on heroic/legendary with the boom and grunt funeral skulls on. When you take the gravlift back into Truth and reconcilliation you will enter in the big room. There is alot of dead grunts on the floor, and since the grunt funeral skull take into effect on every dead grunt, they will explode and with boom on, the grunts under your feet will turn into a methan filled nuke. So 2 secound after you have entered the ship, you are dead. You will also unlock a checkpoint, so there is no way out of the deadly trap, you have to restart the level and turn off the skulls.
must test this just for a few laughs 
I was soo pissed, halfway through the level, and you cant proced Xd I must i admitt i loled a little. But on topic. They need to fix this, this is gamebreaking (at least for slaso`S) Hope 343 sees this, which i doubt, this thread got quickly buried under a lot of stupid hate threads.
I’ll have to try this out. It sounds hilarious!
Post on YouTube please, I gotta see this 
I will make a video, and then update the thread
This sounds similar to what I did with Captain Keyes on T&R (threw a plasma grenade near the activation panel and then activated it) only 10x better.