I used to love building a mega fortress when playing against the AI, biding my time, then using a passage to pop up in the heart of their base and wreak havoc!
I do love Underworld Passage, and the Greeks are especially good with it, combined with their Pegasus. But I must be honest, it isn't even my favourite Greek Heroic Age power. That would be Curse. You think you can win this fight? Nope! Your army is all pigs!
I spent an hour or so today creating my own spreadsheet with all this information, because I noticed that it wasn't in the official wiki.
And then I discovered it is in the official wiki...just buried under an expando on the changelog page. This is a screenshot taken from that changelog.
I also went through and added this information to each god power's page on the wiki for the Egyptians and Atlanteans. Greeks and Norse already had it from someone else.