For me it started with season 15 I believe, or 16. Hell, maybe even earlier. Before that, I had semi-regular Kraken encounters.
After that, it became almost as rare as Shrouded lol. Right now, I'm counting around month and a half since my last encounter. And mind you, I play regularly, around 30h per week at least.
So... what happened? Did they lower spawn chance when they introduced new megs? Or even before, when they introduced Burning Blade? It's been so long since I've noticed this, I can't even remember anymore.
I also spend a lot of time sailing (EDIT: I also NEVER dive), both to the events and between, and it just doesn't wanna spawn on me. I didn't even sight it, let alone fought it.
If the reason for lowering the spawn chance is people complaining about Kraken being a nuisance - that ship has sailed the moment Rare started spamming emergent and patrolling skellies with the Smugglers update, and tons of people complaining on the forum week in and out.
On that note - I didn't mind Skellies in S17 at all, cuz they were free easy loot, and something to break monotony of sailing. But I wouldn't object if Rare raised Kraken spawn, even if it meant lowering the chance of skellie ships in return.
I'm really missing them lol.
