My personal recommendation:
- I recommend buying the 5 builders to get the sixth base, plus you will get a reservoir capacity over 1.8 million (which will allow you to buy the Legendary Hero card for 1.7 million water aprox. in the Warehouse, and you will get 2 roll of 150 gems free).
- Get 10.000 Might to play Lost Realm and Lost Battlefield (in this last, to get free gems). While you don't have 10.000 Migth, use Blue Crystal to Craft equipement and put to Heroes to give them more HP, attack, etc.
- If you are going to buy a Hero of Shards, I recommend first Marid (Minotaur Chieftain, 9,000) and later Suriel (Cupid, 11,000). Marid will help you advance easily into the Dungeons. But maybe you're lucky and get them early for rolling gems or in a free event (for example in Lucky You!)
- If you want to know the events game, you can see it in the guide that there is in the Forum: