Based on Chewy’s post here I thought I’d have a bash at my rankings. S for overpowered then A to D seems an odd way to do it when preferences come in rather than out right power but hey, that appears to be the format.
S
River Surges In Sunlight - great starting cards and a brutal and straight forward innate.
Thunderspeaker - Fast out of the traps and grows in strength in the end game. Has some management needed of the middle stage of progression but if the start is done well you should be in easy street by then.
Heart of the Wildfire - So destructive it’s not even funny. As long as you can run a game on a blighted island (most likely) there’ll be no invaders left.
A
Ocean’s Hungry Grasp - needs an asterisk, the most overpowered partner of any spirit with decent pushing. Great power generation and has deadly control of the coasts. Quick to help the other boards at the coasts should allow fellow spirits to deal with the centre mitigating it’s weakness.
Serpent Slumbering - the defend power is so good it mitigates the slow build. Then the serpent awakes and it’s all over. Rude power and card numbers plus during the escalation buffs other spirits.
Bringer of Dreams and Nightmares - The sheer weight of fear generation and speed with which Bringer runs majors are both astounding. A bit of finesses required but once over that hurdle the efficacy is awesome.
Keeper of the Forbidden Wilds - the numbers get big, real big. Getting there’s the trick though. Has potential to get in trouble with early spread but once they get going they’re so destructive that it should only take a turn or 2 of running at full power to clear the island.
B
A Spread of Rampant Green - putting out allies presence is so good as is the no ravage for presence. That being said can get overwhelmed without some careful management and tails off a bit late game. Hard to rate power wise due to how interactive with other spirits it is.
Lightning’s Swift Strike - being a slow turn fast turn spirit seems to negate the slow powers fast abilities a bit and it’s killing towns and cities is decent without being great.
Vital Strength of the Earth - Defends everywhere isn’t to be sneezed at and once they get going the energy income and ability to get repeats of any powerful cards is good. Just maybe not scintillating to play.
C
Sharp Fangs Behind The Leaves - Really fun to play but can be swingy with the events and if they get thrown off course too badly are a really tough one to recover with.
Shadow Flickers Like Flame - I’m not sure they’re as bad as many make out but still maybe a bit too jack of all trades to really feel like a beast. The Dahan targeting ability is great for their range potential early on and can give some really fast starts but that’s circumstantial.