kraken can spawn only once

krakener.lua

function Krakener:CanSpawn(ignore_cooldown)
   return (self:TimeUntilCanSpawn() <= 0 or ignore_cooldown) and not self.kraken and self.spawn_chance_mod > 0.0
end

--[[ 

This means that the quacken can sapwn if and only if all those conditions are met:

  * cooldown is 0 (you did not spawn the quaken recently)
  * there is no quacken in the world
  * the chance threshold is positive (spawning a quacken is random)
 --]]