User blog comment:Rafe Adler/Major Crossover/@comment-3423279-20160519143054

Mongul

The Imperiex Invasion

Cloneageddon

Man of Steel vs CW's DC series

Some sort of Smallville cross over or reference

Earth Two actually being destroyed by Sam and Dean somehow blowing it up while saving each other. (I am quite peeved with that aspect of Supernatural >.<)