4140,Knight_Of_Abyss_Card,Abysmal Knight Card,6,20,,10,,,,,,,,2,,,,,{ bonus2 bAddClass,Class_Boss,25; },{},{}
* Class (c)
Class_Normal, Class_Boss, Class_Guardian, Class_All
case SP_ADDCLASS: // bonus2 bAddClass,c,x;
PC_BONUS_CHK_CLASS(type2,SP_ADDCLASS);
if(!sd->state.lr_flag || sd->state.lr_flag == 3)
sd->right_weapon.addclass[type2]+=val;
else if(sd->state.lr_flag == 1)
sd->left_weapon.addclass[type2]+=val;
else if(sd->state.lr_flag == 2)
sd->arrow_addclass[type2]+=val;
break;
answer is no ... since rathena changed the monster mode, there are no field for setunitdata to modify a monster into Class_Boss mode
unless ... well ... make an issue in rathena github