KMS 1.2.159 - Magesssss

Speaking of the Demon pet. Each Demon pet has a new skill that adds a passive weapon/magic attack boost. You get a set effect when you have all three Demons. in Tespia it is +10, +10 and +15 for the 3rd pet, which makes it a total of +35 weapon/magic attack.

It's changed in this patch. The first pet (Lv. 1) adds +3 weapon/magic attack, second pet (Lv. 3) adds +5 weapon/magic attack and the third (Lv. 3) adds +7 weapon/magic attack. All of them together makes it +15 weapon/magic attack. To gain this advantage you need all three colored Demons. 3 blue Demons will not get you +15 weapon/magic attack, but only 3.

They're cheap as well. 9.9k for each package.