To be able to unleash this on your characters, the first thing you need to do is unlock the Primal Instinct slot. This will be available to each one of them at their upgrade tree, as the second additional mini upgrade on level 12.
After that, you'll be ready to collect your own character Primal Instincts. They all will be available for you either on daily deals or through Crates.
You can find a list of all available Primal Instincts by accessing his Characters' FAQ by tapping here.
We hope that you can be even stronger with this new feature and that you have lots of fun playing at the Zoo! See you there! :)