The moment her spherical body exceeded the height of her inflator's, Nell's natural abilities kick in and her body fights back against the airflow. Converting all that helium into height; deflating back to her regular imposing form and getting her feet back on the ground. Wick finally realises that something is up just in time to see that he's completely lost control of the situation - and despite his earlier intentions, he's really regretting letting the Obstagoon empty the entire air tank.
This is page seven of a comic commission for VDO featuring their Obstagoon character Nell, and my character Wick.