Gems of War

While not an endgame achievement, this will take a while to get. It is done by reaching 40000 Renown throughout all of your underworld factions. This will take a VERY LONG time to get, and you'll have to get as many factions above 1200 renown, preferably above 1500 or even 1800 renown as possible.

One way to do it is to have three regular faction troops and the Cauldron or Anvil as your hero weapon (This ignores working on 2500 reknown on a single faction). Using the Cauldron as a hero weapon will double the ally's attack and add life to the troop it's cast upon. Keep casting it on your top troop to double its attack and/or keep giving it life to counter the effects of damage by both skull attacks and spell damage. Doubling its attack will make the troop extremely lethal against enemies and will help a lot towards raising the faction renown up considerably. Be careful as sometimes enemy skull damage will risk that troop being lost. You may want to consider casting cauldron on another troop just in case the top troop is lost.

Please note though that this method will not help towards getting 2500 renown on a faction. That must be done with PURE faction troops, that is all four troops are from THAT faction.

Some of you might have better luck with other strategies and faction success but this three troops/one cauldron weapon combo got me much further in various factions, even a lot of the harder ones.

If you decide to go for the "By The Beard of Zeus!" achievement which is earned by reaching 50,000 renown, you'll get this achievement along the way. Good luck and enjoy the long journey towards it.