Check here:
https://www.angrybirdsnest.com/category/angry-birds-epic/angry-birds-epic-walkthroughs/chronicle-caves-walkthroughs/

Make sure your birds are leveled-up and well-equipped!

Check here:
https://www.angrybirdsnest.com/category/angry-birds-epic/angry-birds-epic-walkthroughs/wizpigs-casatle-walkthroughs/

Make sure your birds are leveled-up and well-equipped!

It is okay to post ideas in the forums, no one is gonna torch you. :)

You already get coins from destroying extra items(sand castles yield the most, I think?). Awarding gems might be a bit too…over for Rovio to do ^^.

@triplem As @gradientturtle7 said, your chances of success is very random. My level 8 Optimus Prime got 3 stars “Master Destroyer” but only got 1 level of of success(1 key)!!

@gradientturtle7 Thanks for the clarification! Really helped! Just have one question. There is an achievement that gives you 30 gems if you have 9 Transformers on missions at the same time. How do you achieve that?

@zwizdan007 Thanks for confirming!