[m0oni9]

I have a quick and dirty interim way to implement this.

In Mob::CreateHPPacket(), mob.cpp, about line 688:

   else
   {
      if(IsNPC() && IsEngaged())
        parse->Event(EVENT_HP, GetNPCTypeID(), NULL, CastToNPC(), CastToMob());
      ds->cur_hp=IsNPC()?(sint32)GetHPRatio():cur_hp;
      ds->max_hp=100;
   }

In PerlembParser::Event(), embparser.cpp, about line 184:

                        break;
                }
                case EVENT_HP: {
                        SendCommands(packagename.c_str(), "EVENT_HP", npcid,
                                npcmob, mob);
                }
                default: {

event_codes.h, add:

#define EVENT_HP  9

(imho would look better with enums in here)

You should now be able to make an EVENT_HP sub in your script. You can use the code Monrezz supplied to get access to mob HP, and possibly create another variable (ie: mobHPpercent). The problem with this implementation is that it is (possibly) invoked every time HP updates happen, which is very frequently -- however, I'll note that it didn't affect my load noticeably. I really can't see this being implemented in a way other than using a timer, and calling EVENT_HP sub on engaged mobs, so hopefully this won't be too far off.