This is not really an exploit but i noticed that with the new patch 2.3.2 mages get double the mana from their Emeralds. The mana cost to make the emeralds has however stayed the same.What this means is that if you are in a long tough fight you can sacrifice 1k mana to make the emerald during the fight. Then use it to gain 2k mana back. Not only do you end up gaining 1k+ mana for the first charge but you also get 2 extra charges from the same mana emerald. So u can end up gaining about +5k mana for the cost of the 1k needed to craft the emerald.