// zombified undead) to be placed at stairs.

                // non-spectral zombified undead) to be placed near
                // stairs.

    return (!mons_class_is_zombified(mc));

    return (!mons_class_is_zombified(mc) || mc == MONS_SPECTRAL_THING);

    return (!mons_is_zombified(mon) || mons_enslaved_intact_soul(mon));

    return (mons_class_can_use_stairs(mon->type));

    // Monsters too stupid to use stairs (e.g. zombified undead) are also
    // disqualified.

    // Monsters too stupid to use stairs (e.g. non-spectral zombified undead)
    // are also disqualified.

    // undead can push past zombified undead).

    // or spectral zombified undead can push past non-spectral zombified
    // undead).

This spell raises living creatures slain by the caster into a state of unliving slavery as spectral things. Note that spectral things are incapable of leaving the level they were created on.

This spell raises living creatures slain by the caster into a state of unliving slavery as spectral things. Note that spectral things can follow you beyond the level they were created on.