Sorry forgot to add these when I was working on the bio and more. But here is your forms from balance to berserker to juggernaut drive.

Balance Breaker: Magic increase ten fold, each time you go into this from, it also increases your knowledge by 5x, your physically stronger then any normal devil and other races, but not as strong as the twins dragons, and every 10 seconds your power increase's but not as much as Issei's.

berserker drive: Well it says, it's the darker side of the scared gear, it can fight anything in sheer brawl fight, even the twin dragons, it increases all powers by 30x, but at the cost of your sanity, it keeps getting stronger each time you attack you do magic and even get hit by others, and when it's time. You make powerful dead angel join you and fight with you, which will increase your power even more, but this will destroy your mind even quicker. 

Juggernaut Drive: Does not look as cool as the other forms or just looks normal. But that's the point of the form, when in this form is meant to show the good side of Jet's powers, where it can see every outcome bound to happened to you but not your death, or cause of it, your Illusions can do what you can do. But it increase by 40x, your limit is two minutes if not out of that form it will cost you your life, but the more you go into it the longer you can stay in it, but it does cause a great strain on your mind and body, while in this mode you can do almost anything easily, "Keyword almost." The only thing you can't do is mimic other sacred gears or create things like living. But the more you master this from it will become stronger.