The Demon Form
The Demon form was something Quinn was unable to use against the previous god slayers because in all honesty, he had no idea what the power was or what it did.
It was possible it would be a bad match up against his opponent or like the previous Blood Sucker form that the Demon from had taken over, it could have down sides.
The Blood sucker form doubled all of Quinn's stats but he was unable to use his powers and his HP was at great risk.
Due to the many powers he had gained including that of Qi, his current form mixed with the powers were stronger then his Blood Sucker form, which was why he had stopped using it.
However this was different.
'I need to fight it, I need to stay concious!' Quinn thought. 'Even though there is low risk due to the opponent, there is still a risk and I need to know what this form does.
'I was able to find a way to keep my mind with the Blood Sucker form, so I should be able to do the same here!'