User blog comment:Chaos11394/Any Ideas for new villians for future seasons!/@comment-69.255.188.213-20130101022704/@comment-5619706-20130103020332

Even as just the King of Crossroads, Crowley knew a shitload of things that allowed him to help the Winchesters outgun Lucifer and his demons. When he became King of Hell, he had a vague idea on how to hunt alphas and interrogate them for Purgatory, he and Castiel outmatched even an arguably more ancient and more powerful Eve, Crowley knew of the spell to bind Death.

It's possible, given Crowley's character that he is the one to think of it just now. After all, his power isn't innate--what is innate is his cunning and deviousness. He doesn't strike hard and fast--he prefers the roundabout method that catches opponents off-guard.

And perhaps Alastiar didn't think he needed it, as he already outclassed Castiel as is.