10 Dumbest Decisions Made By Supernatural Characters
3. Castiel Absorbing Souls From Purgatory
In Season 7 we see Castiel absorb the souls of Purgatory in an attempt to make himself God so he can defeat Raphael and take over Heaven for himself. Quickly, the souls he consumed were slowly influencing his morals and disintegrating his body to a point of no return. The souls led Castiel to kill any angel and human who didn’t support him. While Castiel calls himself a new God, Death claims him to be a "mutated angel".
Once he realised the souls were influencing his decision, he tried to do the right thing by releasing them back into Purgatory, but in doing so Castiel accidentally released the Leviathans into the world and killed himself in the process. The Winchester brothers found themselves in the middle of Castiel’s mess and yet again stopped another apocalypse from happening.
Releasing the Leviathan's onto the world caused a massive domino effect with many innocent people losing their lives, Sam and Dean being put back onto the FBI’s wanted list after faking their death and the brothers losing their father figure Bobby Singer in the process.