I need three. I can't find even one! I've killed the three farting rock trolls, didn't get one. Farming the cave troll near the crossroads south of Crookback Bog has been patched out. Where the hell do I find cave troll livers?

Ice trolls are the best reliable source. You can find them during the Ice Giant quest on Skellige. Save before you encounter them in case they don't drop the liver.

I've done that quest. I'm already level 34 and I still haven't come across a single cave troll liver. :(

See if the information here can help you.