S5 E22 - Swan Song: Lucifer kills Castiel
I almost fell out of my chair and nearly had a frickin' heart attack! ...and then watched that scene five more times in a row. So much blood and viscera flying around, I loved how they made it look so real (or, you know, if fallen angels wearing human condoms and walking about blowing other angels up with a snap of their fingers were actually real).
And what does it tell about me that all my favourite parts are the ones with the most gore in them?