Steemit's friend this time I will share what you need when playing Empires & Allies games to upgrade buildings and troops.
Then let's look at this article.
1.Supply Drop.
You need a supply drop to upgrade buildings and tower defense to a higher level, how to get is to build a supply drop that is in the resource.
2.Oil.
Friends will need oil to build your troops and upgrade troops, how to get oil by building Oil Derrick contained in the resource.
3.Steel.
You will need a steel to upgrade the building, if the center has reached level 4, how to get it by building a steel factory in the resource.
that's all from me.
may be useful.
thanks.