Board Thread:Game Discussion/@comment-94.212.73.16-20130926163547/@comment-1063722-20130926200109

Using the summoning stone, summons a level 1 (easiest) version of the boss, doesn't use epic boss energy, and it drops 2 pieces of the material. Summoning usually costs 11 gems for current bosses and 30 gems for past bosses, but there are specials when they are cheaper.