Karina twirls both of her short swords, switching to backhanded hold and dropping one of them as she flips out the small disruption needle she still possesses and throws it before charging in and stabbing both swords through its legs before her daggers come out and start sprouting from the creature's legs, hammering them with different magical effects. With the thing distracted with the half dozen different effects, it doesn't notice you shifting shape and hammering it in the chest. You're glad you had the little wings, as the core was off center, and a single perpetrator would have missed. This thing is far too clever to come back at this level when you and Karina are tired.
You've snatched the core, and you can either take it back with you, or you can consume it.