Potion Flask

I made a special potion to speak with spirits. Whoever wants to talk to them should help me. Spirits talk only about hardships, so we won't bother them for nothing!
The Potion is prepared according to an ancient recipe. A hundred moons waned and waxed a hundred times, since we found out about the power of four! They keep us safe and protect our people, but talk only to the witch. I don't care whether the seeker of spirits wears white feathers or red. This is no man's land, there must be no squabbles!
The Potion needs a special vessel – a big shell. Very big! Find the shell and bring it to me, I'll make a potion.

A fish's splash, a wolf's leap.
A hiss of rain, a stomp of feet.
A howl of wind, an ocean's croon.
Nothing is eternal under the moon!

Kug quag, wingless one! You've brought a good shell. Pure, smooth, big. The potion is very strong, it can turn a regular jar into sand in a heartbeat. Only a pure pearl, born in saltwater, tempered in a roaring storm, warmed by hot sun, may hold the magic elixir.