Feb 4, 2019, 19:4302/04/19
The other source mentioned are the invaders, you will mostly get one random item per attack,some more useful than others.
The invader materials give higher bonuses, but you need to be at least Hero 30 to wear some of them,and 50 for all of them.
In order to attack invaders you need considerable amounts of energy,even if you can make quick progess in the game,by upgrading invader knowledge, and hero experience the amount of "free daily energy" the game gives you is quite sparce.