Steam oozes out of overhanging pipes above, and the hiss echoes one way and then the other... The tunnels twist and turn and again grade downward; there's no way to tell how far down Rex actually IS by now.

Suddenly a second sound accompanies the idle workings of pressurized water vapor; thudding, splattering footsteps. The tendril nearest him goes still, and then shoots back into its hiding spot--or rather, into and then out of a vent behind Rex, along with five or so of its buddies. They latch across the tunnel on wires and outcroppings, drawing tight, creating a net of sorts. It distends as something shiny and blistering red raises a limb to bash it.

Rex can fight it, a megaton fist transfers impulse quite well through the holes of a tendril net. Or he could run, too.