So I would like to see better rewards for the achievements. At the moment they give like 20 gems for using Firestorm 50.000 times for example. Ive been playing for over a year and I still have 20% to go for my 20 gems reward! Seriously Flare for playing so long and using spells or units this many times there should at least be much better rewards than 20 gems or even 1M gold for producing 2.000.000 food. Ive been playing for so long and Im only halfway there! For only 1M gold!!
tl;dr Make achievements/missions less meaningless and give better rewards.