Where the Triumph Card is based on opposition, the Retribution Card is of cycles. In the past, underground cities were built into mountainsides or even directly below the ground. The design had the archaeologists wondering what kind of enemy would drive people to live in conditions like these. Some are certainly surrounded by mystery.
All the underground cities that are spoke of in modern times have surface access. It is more of a deep basement than underground. Before this, underground cities were made by poor people to avoid taxes and conscriptions into the armed forces. Some were only discovered in recent years. Underground cities are always for a defence.
There are underground military bases everywhere in the world. The most interesting is the testimonies of when the U.S. built theirs. It is believed that there is an underground civilization at a very deep level, and rumours that there were caverns at a just below surface level that had beings such as reptilians, giants, and other strange creatures.
Where we see surface living as essential, this is not the same for most alien species, especially those who live deep underground. If we were to colonise space, almost all facilities would be underground as that is safest. Smaller cosmic bodies would have temporary structures, easy to disassemble quickly. On Earth, is a permanent base.
It has been imagined, that from a few centuries ago, humans would aim to live under the ground to allow farming to increase, and yet, we have been dissuaded to. It would make sense as we have had the technology since then. Is this because the Anunnaki have a subterranean caste already there? Are they the farmers that farm humans as cattle?
It would seem so. Reptilians can seem human by using technology. The Elite and the Media that we see may be like forager ants, with the main colony being underground. It is not farfetched. Look at how we are dissuaded at the thought of very common alien life. A continuous cycle of livestock being farmed by aliens works best with ignorance.