This guide is intended to help new players and those struggling with River Surges in Sunlight. It is not intended to be comprehensive, or establish a "correct" way to play this spirit. I hope you enjoy and/or find it helpful.
Theme.
River rushes along, aiding its allies and washing its enemies downstream. It has fantastic card play opportunity, and can go in a variety of paths late game. It is one of the better spirits for spreading its power out around the island, as it can do so without sacrificing the creation of sacred sites, River can flow where it wants and as the game progresses, can build into a roaring path of destruction.
Role.
Early on River wants to use its pushes to move invaders away from building or ravaging, while spreading out to wetlands to gain more sacred sites. River not only can prevent builds, but also excels at setting up ravages that will go poorly for the invaders. As the game progresses River can spread influence all over the island, which makes River a fantastic problem solver, able to quickly react to problem areas other spirits can't get to.
Starting your game.
River is extremely versatile, but I'm going to focus on one start that I find works really well. Your first turn place 2 presence, taking 1 from each track, giving you 2 plays and 2 energy. This lets you flash flood if you need to prevent something nasty, and guarantees you the first tier of Massive Flooding. Placing those first 2 presence make sure you spread to the other wetland on your board, as that will extend the reach of massive flooding greatly.
Your second turn take a card and place the second presence from your card play track, looking to spread into wetlands on other boards or get closer to problem areas.
On your third turn you have 1 card and your next growth will get you 3 card plays. Don't Reclaim. It is tempting because no one likes to gain a third card play and not even use it, but here is a great opportunity to place 2 presence and unlock the Reclaim 1 space. As soon as you unlock it, get a card back and you can play 2.
You now have a major advantage over most spirits, as you will play more cards, replay the best cards more, and reclaim all less than other spirits.
You are 3 turns in, and are in great shape to activate tier 2 of flooding almost every turn. Massive Flooding is amazing and will let you break up clusters of invaders with ease.
Advancing into late game.
With the turn 3 reclaim start, you are well set up to go for a Minor power heavy build, or to head toward getting Major powers. Turn 4 you will need to reclaim all, and after that you should have a few energy saved up and you can either push for your 4th card play and gain a new minor power, place 2 presence to get 3 energy a turn, or hedge your bets and gain a minor power while placing the second energy track presence. Again, River is incredibly versatile and can branch in new directions at almost any time.
Power card guide.
While River can go in many directions, it is important to remember that your 2nd tier flooding is stronger than a minor power, and 3rd tier is as good as many major powers, and very few major power element thresholds will be better than flooding.
With tier 3 flooding requiring 4 water, you ideally want every card you have to give you water. Fortunately there are a lot of them, and 8 minor powers that have both water and sun, which, when you add in your reclaim 1, is very promising for a minor power deck focused on activating your innates.
As for effects, River works so well as a problem solver that almost any effect will find use somewhere on the map, and it is unlikely you won't be able to reach that spot.
My favorite minor powers for River.
Encompassing Ward. Sun, water and earth are all there and defending 2 everywhere you have presence is a fantastic effect for a spirit that spreads out like River does.
Gift of Power. I wish it had sun, but it still accelerates your power gain and reduces Reclaim all frequency by a good bit. Getting this early can really boost River's ability to finish both tracks.
Cycles of Time and Tide. More Dahan, water and sun, blight removal. Fantastic card unless Ocean is in the game, because then there isn't much need to assist on the coast.
Sky Stretches to Shore. Sun, water, earth and my favorite combo yet of Flash Flooding and tier 3 Massive Flooding clearing a land that had 2 cities, 4 towns and 3 explorers before it could ravage.
Favorite major powers for River.
Cleansing Floods. This was made for you. You should occupy every wetland and never fail to have 4 water.
Swept into the Sea. Low cost, easy threshold to reach, and you like things on the coast. Using this to gather a ton of towns together for tier 3 flooding to demolish is amazing.
Fire and Flood. Two lands, 8 and 4 damage.
Either of those first two make River a juggernaut of doom, as the cost and thresholds make them powers you can use frequently and powerfully.
Final tips.
1. Protect your wetlands. Losing presence in wetlands can really hurt, keep your centers of power safe.
2. Wash Away and Massive Flooding are stronger than you might think, and will do a lot to keep your home board safe early on. Together they can turn 2 builds into 0 ravages of danger.
3. Play River's Bounty as often as you can, the energy gain and extra Dahan make for a smoother game. Remember that the check for 2 Dahan works even if you don't gather or just gather 1. You can easily fill your board with an army of Dahan and support more power cards by playing Bounty frequently.