Blight represents environmental/spiritual harm to the Island. Blight is added to the board and Blight Card/Space during setup. If all Blight is removed from the Blight Card/Space, you lose. After setup, Blight is added whenever Invaders cause 2 or more damage at once to the land. Adding Blight to a land destroys one Presence from each Spirit with there. If Blight is added to a land with Blight, another Blight is added to any adjacent land.
The Dahan’s agriculture and animals brought Blight to the land and conflict with the Spirits, triggering the First Reckoning. The Dahan capitulated quickly, and an accord was reached: the Spirits would tranform crops and animals to be more compatible with the ecosystem. The Dahan would change their methods of farming and seek counsel from friendlier Spirits. The two became neighbors, though unequal: the Dahan were reliant on and obligated to the Spirits.
Now, Invaders slowly but inexorably Blight the land. A certain amount of Blight is normal in nature - such as damage from a forest fire - but too much will overwhelm the island. 
Blight: A piece showing environmental/spiritual harm to the Island.
Blight Card: A card that holds the Blight pieces that are not on the Island. Starts off on the Healthy side, and may flip to the Blighted side during the course of the game.
- Blight Space: Optionally used instead of a Blight Card, reduces complexity. Follow the instructions on the Invader Board instead (5 per player).
Blighted Island: The Island becomes Blighted when all the Blight on the front of the Blight Card goes onto the board. If all Blight on the Blighted side runs out, the players lose.
Populate the Island Boards with Invaders, Dahan, and Blight (from the box) as indicated by the icons in each land.
Extra Island Board
Base the size of your Blight pool on the number of Island Boards rather than the number of players, both during Setup and when flipping a Blight Card. 
- Set up Dahan, Blight, and Spirit tokens ( , ,etc.) on the extra board normally.
Do not place any Invaders or Blight indicated by Adversary Setup instructions on the extra board.
Take a random Blight Card and place it on top of the Blight Space on the Invader Board, “Healthy Island” side up, without looking at the back. Place the number of specified on the card (generally 2 per player), + 1. This 1 extra blight only goes on the Healthy side of the card (not Blighted Island)
Blight Cards which have only 2 Blight per player on the Blighted Island side can be especially nasty when playing solo. If you get one of them in a single-player game, you may choose to draw a random replacement from among the unused Blight Cards.
"Still Healthy" Blight Cards
Two of the new Blight Cards say “Still Healthy” on the opposite side and have a small Blight pool. When this Blight pool runs out, you do not lose – instead, following the instructions there, you draw a new Blight Card and go straight to its reverse side (which may be “Blighted” or “Still Healthy”).
- Setup Change: Because you might need more than one Blight Card, simply put the entire shuffled stack of Blight Cards atop the Blight space, and use the top one. Should you need another, just use the next one in the stack.
Playing with Events
Playing with a Blight Card is now required rather than optional. (The Event Deck depends on using one.)
- Events happen AFTER blighted Island Effect and before any Earned Fear Cards.
- You can either pull those cards out before shuffling, or redraw if you get one. Without an Event Deck to provide occasional Blighted island Events, cards with beneficial or non-ongoing effects become much lower-risk.
Still-Healthy Island Cards are fine, though staying Healthy has less game impact.
No Blight Card
If you are not using a Blight Card, use the Blight instructions printed on the Invader Board instead. Place the shown amount of Blight onto the card from the box, +1 as in the case of using a Blight Card.
Blight spreads quickly once it starts cascading. Try to clean up lands before a second Blight is added.
Where should I put my presence/sacred sites?
Avoid lands where Invaders are about to Ravage and add Blight. It will destroy your Presence.
Notable Island Layouts
When a lower Coastal land (land #3) is not adjacent to another board, Blight cascades in that corner can get bad very quickly due to limited adjacencies.
During Setup, once you’ve put Blight on the Blight Card and the Island, return the rest of the Blight to the box. This prevents accidently taking Blight from/returning Blight to the wrong place! It’s easy to access the box a single time when the Island becomes Blighted.
Can't Remember Blighted Island?
If you have trouble remembering to follow the instructions once the Blight Card has flipped to "Blighted Island", put a Blight from the box onto the Fear Space as a reminder. 
Game Too Hard?
Two Blight rules can make the game extremely punishing if misplayed. Ravaging adds only one Blight to a land (not one per 2 Damage!), and Blight only cascades to a single adjacent land (not to all of them!)
Blight Card Never Flips?
You are having a crushing victory; the game is too easy for you (barring any egregious rule violations). You could probably increase the Difficulty by 2. 
Selecting Blight Cards
Blight Cards are meant to provide some uncertainty – both about how much will be available after it flips, and in what the ‘twist’ will be. Beyond that, the exact set of cards to pick from isn’t tremendously important, so if there are a couple of Blight Cards your group finds too extreme, too sedate, or just un-fun, feel free to simply not include them.
Even if an Event changes the Ravage Step to a Build Step, “Migratory Herders” (gathering Towns into lands slated to Ravage the following turn) still activates as normal.
When playing with Durable Invaders (Habsburg Level 4+) and Ocean’s Hungry Grasp: Drowning is a special form of Destroy, and only grants Energy if the Destruction succeeds. E.g., when you move a Town into an Ocean, the Town takes 2 Damage. If that’s enough to Destroy it (because the Ocean has Blight or the Town was already Damaged), then it Drowns normally. Otherwise, it washes ashore, Damaged, in an adjacent land. (It can’t stay in the Ocean, so gets placed in the nearest legal land, per p. 28). If the land it washes ashore in has Blight, it will immediately be Destroyed, but Ocean’s Hungry Grasp will not gain Energy. If 4 undamaged Towns are pushed into the Ocean with a single Action, that results in “8 Damage to Towns only”, which you could distribute as you wished. If you used it to immediately Destroy 2 of the Towns, those Towns would be successfully Drowned and grant Energy.
Scenario: Second Wave + Still-Healthy Island Cards
Still-Healthy Island Cards aren’t addressed by the rules for Blight continuation for the Second Wave. Either don’t use them together, or follow these instructions (which are a convoluted way to say “rewind cards, and what you learned doesn’t change”).
If you went past a Still-Healthy Island Card, after following the Blight instructions, put it – original Healthy side up – atop the stack of Blight Cards (so you encounter it first, just like you did this game).
If you reached (but did not pass) a Still-Healthy Island Card, treat it as a Blighted Island Card for the Blight instructions – but in your next game, if you get past it to a new Blight Card, you will need to add new Blight from the box rather than from the pool by the side of the card.
Spirit: Stone’s Unyielding Defiance
In the last level of Hold The Island Fast With a Bulwark of Will, “When an Event or Blight Card directly Destroys ” means it uses the words “Destroy ” rather than, e.g., adding Blight that then happens to Destroy Presence. This Innate’s effect can be used even if the Presence Destruction was paying a cost or otherwise optional.
The second level of Let Them Break Themselves Against the Stone modifies the triggered Action created by the first level. So, for instance, in a land with 1 , only increase the retaliation Damage by 1 each time the Invaders deal Damage.
Blight is not component-limited.
New Turn Order
(All play is simultaneous)
- Gain Energy
- Play and pay for Power Cards
Fast Power Phase (Cards and Innate)
- Blighted Island Effect
- Event (except first turn)
- Fear Effects
- Ravage (Including Strife)
- Build (Including Disease)
- Explore (Including Wilds)
- Advance Invader Cards
Slow Power Phase (Cards and Innate)
- Played Power Cards go to personal discards.
- Damage and Elements go away.
Other Mentions in Rulebooks
Victory or Defeat: +1 per X living Dahan and -1 per X Blight on the Island, where X is the number of players in the game.
This Adversary is notably easier for Spirits that tend to let lots of Blight get added (e.g., Vengeance as a Burning Plague) or for Spirits that can Isolate lands (e.g., Downpour Drenches the World).
This Adversary is notably harder for Spirits that are hamstrung by Blight (e.g., Sharp Fangs Behind the Leaves) or with Scenarios that involve keeping the Invaders from reaching a given place.
A few things can initiate base Actions in the middle of other Actions – e.g., Fractured Days Split the Sky has an Innate Power with “Target Spirit may Resolve 1 Power now”. In cases like this, you pause the current Action, Resolve the entire new Action-tree (base Action and anything triggered by it, directly or indirectly), then return to the original Action.
This most commonly happens in two cases: when the Blight Card flips and has an immediate effect (you follow its instructions before continuing with the Action that added the final Blight) or when a Choice Event includes “Each Board” or “Each Spirit” instructions. (Most of the Choice Event is a single Action, but the “Each” instructions cause a number of new base Actions.)
Notes & FAQ
- Base Game: Lore: Dahan, pg. 24
- Base Game: Game Concepts: Blight, pg. 15
- Base Game: Reference: Glossary/Index, pg. 30
- Base Game: Game Setup: The Island and Supply, pg. 6
- Base Game: Gameplay Options: Adversaries: The Kingdom of Sweden, pg. 22
- Jagged Earth: Play Options: Including an Extra Island Board: Game-Wide Rules and Changes, pg. 18
- Jagged Earth: Play Options: Including an Extra Island Board: Setup for the Extra Board, pg. 18
- Base Game: Game Setup: Invader Board, pg. 6
- During Setup, you get exactly 1 additional Blight in your Blight pool https://querki.net/u/darker/spirit-island-faq/#!one-more-blight-errata
- Branch & Claw: Rules Updates: Solo Play, pg. 17
- Jagged Earth: New Game Items: "Still Healthy" Blight Cards, pg. 9
- Branch & Claw: Branch & Claw: Setup Changes, pg. 7 | Jagged Earth: New Game Items: Setup Changes, pg. 6
- Branch & Claw: Event Cards, pg. 8 | Jagged Earth: New Rules: Events, pg. 12
- Jagged Earth: Play Options: Playing Without Events, pg. 20
- Branch & Claw: Rules Updates: Invader Actions: Invaders Doing Damage Multiple Times in Same Land, pg. 15
- Jagged Earth: Appendix: Clarifications and FAQs: Blight, pg. 28
- Base Game: Game Concepts: Power and Fear Effects: Removing Blight, pg. 18
- Jagged Earth: New Rules: Isolate, pg. 10
- Branch & Claw: Rules Updates: Blight, pg. 15 | Jagged Earth: Appendix: Clarifications and FAQs: Blight, pg. 28
- Base Game: Tips & Tricks: Basic Strategy: Miscellaneous, pg. 21
- Base Game: Tips & Tricks: Basic Strategy: Where Should I Put my Presence/Sacred Sites?, pg. 21
- Jagged Earth: Play Options: Island Layouts, pg. 16
- Base Game: Tips & Tricks: Streamlining Gameplay, pg. 20
- Base Game: Sequence of Play: Invader Phase, pg. 8
- Base Game: Reference: Adversary & Scenario Difficulty Chart, pg. 28
- Jagged Earth: Appendix: Clarifications and FAQs: FAQs on Specific Game Items: Adversary The Habsburg Monarchy, pg. 29
- Jagged Earth: Appendix: Clarifications and FAQs: Scenario Second Wave + Still-Healthy Island Cards, pg. 31
- Jagged Earth: Appendix: Clarifications and FAQs: Spirit Stone's Unyielding Defiance, pg. 31
- Branch & Claw: Reference: New Turn Order, pg. 24 | Jagged Earth: Clarifications and FAQs: New Turn Order, pg. 36
- Jagged Earth: New Rules: Actions, pg. 10
- Base Game: Gameplay Options: Scoring, pg. 23
- Jagged Earth: Adversaries: The Habsburg Monarchy, pg. 22
- Jagged Earth: Appendix: Actions in Detail, pg. 25