User blog comment:EmpyreanSmoke/Weaknesses/@comment-27036944-20151002015940/@comment-3481504-20151124014013

Leviathan can kill any type of celestial beings, therefore meaning reapers, cupids, angels, Rit Zien, grigori, seraphs, and even archangels. Both death and Cas were definitely making a generalization with this by saying "whole petri dish"/"whole aquarium," which is to refer to all of creation at large. Um, yes.. "petri dish" refers to the Earth, but I would say he meant it to mean God's work as a whole.