[AndMetal]

From what I can gather after looking through the source, we didn't used to take into account the chance the spell had to proc, which I believe is what Wolftousen was trying to correct (and for the most part did). That's what iChance is for in Mob:AddProcToWeapon():

bool Mob::AddProcToWeapon(int16 spell_id, bool bPerma, int16 iChance) {
	if(spell_id == SPELL_UNKNOWN)
		return(false);

	int i;
	if (bPerma) {
 		for (i = 0; i < MAX_PROCS; i++) {
			if (PermaProcs[i].spellID == SPELL_UNKNOWN) {
				PermaProcs[i].spellID = spell_id;
				PermaProcs[i].chance = iChance;
				PermaProcs[i].pTimer = NULL;
				mlog(SPELLS__PROCS, "Added permanent proc spell %d with chance %d to slot %d", spell_id, iChance, i);

				return true;
			}
		}
		mlog(SPELLS__PROCS, "Too many perma procs for %s", GetName());
    } else {
		for (i = 0; i < MAX_PROCS; i++) {
			if (SpellProcs[i].spellID == SPELL_UNKNOWN) {
				SpellProcs[i].spellID = spell_id;
				SpellProcs[i].chance = iChance;
				SpellProcs[i].pTimer = NULL;
				mlog(SPELLS__PROCS, "Added spell-granted proc spell %d with chance %d to slot %d", spell_id, iChance, i);
				return true;
			}
		}
		mlog(SPELLS__PROCS, "Too many procs for %s", GetName());
	}
    return false;
}

However, I don't think there's any need to change the calculation for the chance to proc, just make sure we're taking it into account:
zone/attack.cpp

		if (SpellProcs[i].spellID != SPELL_UNKNOWN) {
			int chance = ProcChance * (SpellProcs[i].chance);
			if(MakeRandomInt(0, 100) < chance) {
				mlog(COMBAT__PROCS, "Spell proc %d procing spell %d (%d percent chance)", i, SpellProcs[i].spellID, chance);
				ExecWeaponProc(SpellProcs[i].spellID, on);
			} else {
				mlog(COMBAT__PROCS, "Spell proc %d failed to proc %d (%d percent chance)", i, SpellProcs[i].spellID, chance);
			}
		}

The biggest problem we're running into now is the default for SpellProcs[i].chance for several spells is 0, so we're multiplying by 0. What we should probably be doing is adding a percentage if it's not zero.

From the PEQ Forums:

This will fix any proc that comes from a buff/spell. CD has the new fix for it that will make these procs account for the PROC_RATE_MOD you find in a lot of their discriptions (this was previously not being taken into account). So for BL pets, they will proc 1.5x as much as a normal character with their stats would with that proc (BL pet buffs have a mod of 150...), spirit of puma willl proc 4x more, etc...

If that's the case, we should be able to change this in zone/attack.cpp:

		int16 spid = SpellProcs[i].spellID;
		if (spid != SPELL_UNKNOWN) {
			int8 spc = SpellProcs[i].chance;
			int chance = ProcChance;
			if (spc > 0) {
				chance = ProcChance * spc / 100;
				mlog(COMBAT__PROCS, "Proc mod on spell proc %d (spell %d): adjusting chance from %d to %d (%d mod)", i, spid, ProcChance, chance, spc);
			}
			if(MakeRandomInt(0, 100) < chance) {
				mlog(COMBAT__PROCS, "Spell proc %d procing spell %d (%d percent chance)", i, spid, chance);
				ExecWeaponProc(spid, on);
			} else {
				mlog(COMBAT__PROCS, "Spell proc %d failed to proc %d (%d percent chance)", i, spid, chance);
			}
		}

That way if it's 0 or negative, we don't mess with it, and if it's 400, we're multiplying by 4.

On a side note, there's a potential issue that could break this when zoning. From zone/client_packet.cpp:

                case SE_WeaponProc:
					{
					AddProcToWeapon(GetProcID(buffs[j1].spellid, x1), false, 100+spells[buffs[j1].spellid].base2[x1]);
					break;
					}

We should just be able to remove the 100+, and it should be good to go:

                case SE_WeaponProc:
					{
					AddProcToWeapon(GetProcID(buffs[j1].spellid, x1), false, spells[buffs[j1].spellid].base2[x1]);
					break;
					}

I don't have a server up right now to compile & test, so if someone wants to give this a shot, feel free.