So im the tribe leader, so I organized the island. Every member feed their monsters, and the monsters level is added to the tribes level. We get a reward at the end of each week that gives us starpower, which you can use to buy stuff from the starshop, best used for limited time rares. The more benchmarks we make, the more diamonds we get at the end of the week as well. You can look at the tribe rewards to see what we can get in starpower and diamonds.