In Dragon Ball Super, when fighting Hit, Goku used the super saiyan blue kaioken or also called super saiyajin god super saiyajin kaioken. With this technique, he could get even 10 times stronger. But now he's inferior to Black, and he has been defeated 2 times by him, but he doesnt use it as a last resource. Why is that?
There are a ton of disadvantages using Super Saiyan Blue Kaio-ken:
- It has only a 10% chance of working and a 90% of failing, which had a chance of killing him.
- Goku is only able to maintain Super Saiyan Blue Kaio-ken x10 for short periods of time because it puts a great deal of strain on his body. While Potara fusion could last for an hour.
- Goku began to suffer severe muscle convulsions as he powered back down to base form and developed Delayed Onset Ki Disorder which includes significant decrease in ki control and capacity.
- King Kai warned Goku to not use this form as the user might incapable of getting stronger.
Though, Goku did used Super Saiyan Blue Kaio-ken once to escape Fusion Zamasu's grasp and send him flying with a swift kick. Goku manages to destroy Fusion Zamasu's Ring of Light, but quickly returns to base form, unable to move. See here for more details.