Originally Posted by
Meiffert
You don't specify a difficulty you are trying to do.
There is some good advice in this thread already, but one thing I want to mention in case you are talking about heroic is this: heroic KJ (and other last bosses in other heroic raids) are not supposed to be pugged.
The fight is difficult. Most top guilds wiped a couple of times before they got him down the first week. And we are talking some of the best players in the game with awesome coordination, used to calling and using externals/raid cooldowns, very high individual performance and PTR experience.
If they couldn't one-shot it, how do you expect to do it? And ultimately you only have a few attempts in a pug before someone leaves. As you replace people, you have to start over.
There are successful groups on heroic KJ for sure. But these groups have people who are 7/9m, 5/9m or at least 9/9hc multiple times by now.
With their experience of killing the fight multiple times, they can now do it with limited coordination of a pug and even then it's not exactly easy and rarely do you get a clean kill or a 1-shot.
To get the boss down the first time, you have to make continuous progression. Most groups who haven't killed it by now will likely require multiple nights to do it. It's hard to have a pug run long enough without disbanding to learn the boss.
The best advice I can give you is to not progress hard bosses in pugs. You can do them in a pug - later on when you and everyone else in the pug has the experience of killing the boss, but for progression you should really join a stable group.