Pet exploit
Maxing pets is tedious, and requires a lot of resources, and fusing them eliminates one of your pets... but not really! It is possible to keep the pet that is normally lost during fusing, if you have it follow other characters on your account before fusing.
It's really that easy. Change characters, have the pet that you're going to put in the 2nd fuse slot follow you, then switch characters again. When you fuse the 2 pets, your lower rarity one remains.
Here's the bug though: You will no longer be able to feed this pet. If you attempt to, the higher rarity fused pet appears; so make sure it is as maxed as you want it before you do this.
You CAN still fuse this pet though, and here is the exploit. With the proper planning, you will need many fewer pets to reach the final rarity phase. You'll still need 2 legendary pets to make a divine, but you'll only need 3 rare pets to make those legendary ones, only 4 uncommon pets (instead of 8) to make those rare pets, and only 5 common pets (instead of 16!!!) to fuse into uncommon. This is a huge savings.