Livina Lightfoot
Livina reels from the crushing blow, but she still finds the strength to lash out once more with the heavy mace, trying to at least put a dent in the creature's massive leg.
She nods at Kizima
I hope you've got a plan...
Regardless of the effect, Livina leaps and curls inward as she passes directly over Krashnix's head, back down the stairwell. once past, she shoots her arms and legs outwards to catch the walls of the narrow stairwell before dropping harmlessly to the ground.
Spoiler
(assuming Flanking)
Attack - (1d20+11)[26] (magical effects of mace not added)
Damage - (1d8+3)[9] (magical effects not added)
Tumble - (1d20+13)[19]
Oops, double-post. I suppose it's fair to use the first attack roll, and let the tumble roll stand?