A few months ago I had a dream where I played a new kind of salmonid wave. I've tried my best to illustrate it and try to tell everyone about the thing I've experienced.
Now introducing : Oil spills
Oil spills are a special wave in salmon run, similar to glowflies or Goldie seeking.
When an oil spill starts, you get a unique piece of Grizz dialogue : "Urgh ... Alright kids you know what ? No objective for that wave. Just try your best to survive."
The round plays similarly to a cohock charge, and golden salmonid starts emerging from the sea. They look like mini cohozunas and are around twice as big cohocks. They are very bulky but walk very slowly, so timing your canon shots is key to get rid of them.
You can get golden eggs from these enemies but picking them up isn't necessary, as there is no quota.
As the wave keeps on going, the golden enemies get slowly and slowly less shiny and more covered with a dark substance. And the more covered they are, the bulkier they get. Until finally, you end up seeing some of them pitch black, basically a mangled salmonid covered in a very thick black dripping goop
These salmonids are completely unable to be killed. They cannot be damaged and in fact, they should NOT be approached. And that's when the wave goal shifts
There ends up to be around 4-5 of these salmonids. They are slow but they will kill you if they touch you. You can technically be revived but the problem is reaching anyone who died. The ink they leave behind is oil, which cannot be covered back by your own ink.
The goal after that is to actually move as a group to properly lure the oil salmonids so that they don't immediately cover up your ground and kill you all. The oil on its own won't kill you but it obviously makes it difficult to move around if you're on it.
When the wave ends, one of the oil salmonids runs up to the egg basket discords its body to swallow it before leaving back to the sea, basically taking away any amount of egg you could've gotten for Grizz (hence why it's NOT recommended to pick up eggs)
If you win, no matter what wave you're on, the shift will end with a victory and Grizz will go "there you go kiddo, we're done for that shift. What, paying you ?! Alright ... I guess I LEGALLY have to pay you even if you didn't do anything. Actually, maybe try dying next time "
Surviving that wave will not give you points for the gatcha, due to your team basically loosing all its eggs. It will, however, give you fish scales based on how well you defend yourself against the mini golden cohozunas
In the darkened sky of the special wave, you may be able to spot aurora borealis, mimicking the colors of an oil spill.
OH and one last thing : this wave had a different kind of music.
It was drums, very intense but not fast paced ones, without any other instruments to accompany them.
If you want an exemple of what this may sound like, listen to Arceus's theme.