Best way is probably to find the code that does the regen, and times it by some multiplier if the mob has no agro.
At a glance, maybe something like this..
line 473 of zone/npc.cpp
Code:
if(GetHP() < GetMaxHP()) {
if(GetOwnerID()!=0 && !IsEngaged()) //pet
SetHP(GetHP()+hp_regen+bonus+(GetLevel()/5));
else
SetHP(GetHP()+hp_regen+bonus);
}
change to:
Code:
if(GetHP() < GetMaxHP()) {
if(GetOwnerID() !=0 && !IsEngaged()) //pet
SetHP (GetHP() + hp_regen + bonus + (GetLevel() / 5));
else if (!IsEngaged())
SetHP (GetHP() + hp_regen * MULTIPLIER + bonus);
else
SetHP (GetHP() + hp_regen + bonus);
}
where MULTIPLIER is some arbitrary number.