Space marines ( in this case, a marine from the ultramarine chapter ) are very strong genetically enhanced super-humans that wear reactive armor (dosen't actually work on minecraft) that make them even stronger. they are hard to kill and are taller than a regular human (dosen't apply here) and have ben known to lift up trucks (read the ultramarine omnibus by graham ncneal (black library publications) or read the space marine codex / look up space marines online for more details)