Before heading to the stairs, Henry carefully takes something (a pole, furniture, anything effective) and blocks the door to the strange water feature. Preferably he entwines it in the handles too, trying to prevent anything from coming out of that room to attack the party while their backs are collectively turned.

At the next ramp he takes a deep breath and looks back to be sure everyone is ready. Once he has all their attention he begins a slow countdown, using his raised right hand to demonstrate. 5-fingers, 4-fingers, 3-fingers...

Once he holds only a closed fist he silently rushes up the ramp as quickly as he can, intent on attacking anything that threatens him as he ascends higher into the strange tower...