Feels like Hisoka has a trick up his sleeve or something. I would say it's because he's having so much fun but.. the guy has been waiting so long for this fight, he's bound to be having fun.
I don't think Hisoka will get killed, I have a feeling he's just getting a feel of Chrollo's abilities. It wouldn't be wise to jump head-first into the unknown. Plus, he likes messing around in his fights for a little bit first.
He's been waiting ages for this shit, why wouldn't he enjoy himself? Overall though, pretty great chapter. Hope Togashi can continue pumping them out and concludes this fight before going on hiatus again. 5/5