The Octo Expansion is pretty hard in places, some real challenge, but also super rewarding. It gives story elements behind Off the Hook that were not really a part of the main campaign, as well as follow up for Cuttlefish and Agent 3, and more of what is happening with the Octolings that many turned against DJ's rule.
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Through dream I travel, at lantern's call
To consume the flames of a kingdom's fall