The Seasons of Inis expansion, as seems to be tradition with the Madagot Trilogy, is presented in modules, giving you the option of adding and removing portions of the expansion material as you see fit. Five total modules are included and I've broken them down by my order of preference:
1. Fifth Player/Clan Added. If you read my Best of 2019 article, this addition of the New Clan was exactly what I was looking for. It is my favorite color to play as (Black) and seamlessly adds a fifth player to the game. An extra player also means the inclusion of new Season Cards that are almost on par with the virtually perfect selection of Season Cards in the base game. The new cards are so good that I really miss them when I have to drop down to anything below a five player game and need to remove them. The addition of a 5th player doesn't upset the delicate balance found in the base game and, maybe just as importantly, doesn't add significantly to the play time.
2. We Need a King. This one is an absolute requirement for a five-player game but should also be used at all other player counts. Occasionally, with the base game, the game time would stretch out if the players tied for the lead were not the Bren. With the addition of the 5th player, this is even more likely to happen. This addresses that issue, essentially putting a timer on the game once one of the objectives has been reached. I don't know if you can call it a full module (it's just one two-sided tile that you place on the table) but it is a rules adjustment that is welcome if you have ever have experienced one of the those seemingly never-ending games of Inis.
3. New Epic Tales cards. I discussed my love for Epic Tales cards in the Madagot article that me and Jackwraith wrote awhile back. More hand of god moments are a good thing and, of the 15 new cards that are added, only one is specific to the fourth module (Ports and Islands) and can be removed if you choose not to play with Module Four. They include the typical “You can do what now?!?” cards and a bevy of others that you can literally build a entire strategy around. Since they are shuffled into the starting deck of Epic Tale cards, it will take a few games before you see them all come out. None of the new cards stand out as overpowered (at least no more OP than those in the base game).
4. Harbors and Islands. I always joke (and will continue to joke until someone actually laughs at it), that Seasons of Inis adds the Obelisks from Kemet to Inis. What it does add is Ports. And the capital city always has a port added to it at the beginning of the game. This means it is accessible from any island or any other territory with a port with a single movement. Thus, it allows you to “teleport” (a.k.a. sail) from various areas around the map right onto the doorstep (seastep) of the capital city. Before, when a Bren held control of the capital, they were allowed to pick the placement of new territories and could choose to place all “newly discovered lands” far away from their stronghold if they weren't going to be the one holding sway over them. This helps mitigate that advantage. At the same time, and in direct contrast to what I just said about ports making areas more accessible, creating a Island Stronghold is now a temptation. Sure, if you math it out, Islands usually end up having just as many (if not more) points of access to them but there is just something so satisfying about building an Island fortress. Six new territories tiles are added (along with the advantage cards for controlling them) and they make great use of the new harbor rules.
5. The final module is actually the one the expansion is named for: The Season mechanic. When using this module, there is an additional step in the Assembly Phase and both Summer and Winter add a different rule/modifier to the game every “season”. This is the module that I rarely use because I don't feel that the randomness it adds is needed (or worth the effort of keeping track of.) It can make it easier for a player to recover from a misstep early in the game but the “A different rule is added or subtracted every round” is just a layer that Inis doesn't need and I feel it interferes with the fluid flow of the game. Maybe someday I will think that Inis needs this to mix things up but I haven't reached that point yet.
Since the Seasons of Inis expansion adds five modules of which I will always use four of (when applicable a.k.a. A Five Player Game), the rating is pretty much a forgone conclusion. As with most sleek expansions, I wouldn't hesitate to add everything but the Seasons Module to even an introduction game. If you have EVER not been able to play Inis because of the four player limitation (which has happened to me on more than one occasion), you know why I picked this expansion up. I wouldn't say everything else is gravy but that is the meat of the reason of why I purchased it. As with most of the expansions for the Madagot trilogy, it is a bit on the pricey side (MRSP is $49.99 U.S.) but I feel it was well worth it.