I realize that the Tattoos just came out in this last update... and that some, if not most, will buy one or more, and for the same reason one gets a tattoo in real life, because we like how it looks...
If, however, the devs are gonna set the price at a relativly steep 10 diamonds per tattoo, perhaps we should request a little more 'bang' for our hard bought or hard won diamonds...
What I have in mind is to pair each tattoo to an ability or stat boost, similar to the also new Atelier function in the Shop.
Several tattoos which have a similar 'look' could also be made as tattoo sets which could react synergistically, like the item sets in HeroZero...
Just a suggestion...