Unlimited summon glitch allows you summon repeatedly until you can 5-stars equipment. After a few attempts without success, you can reset your gems back by performing this glitch.

1. The glitch requires 2 apple devices staying connected to the Internet. How it works:
2. Keep device A open, then use device B to perform summon. You can either summon 1, 3, or 5 times and then reset gems is up to you. 
3. If you haven’t got 5-stars equipment after summoning 5 times, go to device A, press “Quest” menu, then cancel. It will prompt you to select which file data you want to reload “Local Data” or “Cloud Data”. Local data is your device A current stats while the cloud data is the stats from device B where you spent your gems summoning 5 times. Choose local data.
4. Go to Device B, cancel Summon menu, it will prompt you to load data from “local data” or “cloud data”. This time choose “cloud data” (from device A).
5. Repeat the steps above. In case you summoned 5-stars equipment, you can do it in reverse by keeping local data from device B. On device A, you will have to choose data from cloud.

Here is a demonstration: