My first reaction to Pyke...

I wish riot would make a champ that's actually scary.

I mean if you are going to do horror, you should go for something actually disturbing or horrifying. You should go for something that comments on humanity and makes people think. Maybe allegorical for real life events. Take Godzilla. When it was released, the fire bombing of Tokyo and two cities getting nuked by an unstoppable war machine Japan had provoked was fresh on everyone's mind. A giant monster that Japan was unable to defend against made sense for the time. Poe's writing worked because it dealt with madness most of all. Lovecraft worked in the form of hint unreliably after you've built a base of madness.

Pyke seems like a satire aimed at 12 year olds. "I got fed to the fishies and now I'm back for revenge, garr!"

On that note, he looks rather human for a walking pile of fish shit. I mean you'd think after the Last Jedi debacle, your hype team would know what Checkov's Gun is by now. If you are going to hint that he was eaten by a giant fish, then I'm expecting something that would look digested, or at least thoroughly chewed up and missing a chunk of his body and not a generic bloated corpse that drowned.

Now if you want to go with drowned corpse coming back for revenge, then you needed to have shown that he died by drowning or freezing to death in the water. Get rid of the fish entirely. Maybe put a few obvious holes in his story, just enough to make him seem unreliable. Better yet, make him have gone crazy and then he jumped off the ship. Something terrible happened on the boat in the middle of the ocean and he tried to escape the only way his panicked mind would allow and now he's back to warn others about whatever it was.