[Criimson]

I added a couple mes spells to the chanter bot list from:
Mes spells

INSERT INTO `npc_spells_entries` (`id`, `npc_spells_id`, `spellid`, `type`) VALUES (8146, 705, 292, 2048);

Is one of the early ones. And you are right the code starts to fire. !addMob starts spamming the screen during each fight, but even when there is an add it doesn't seem to realize it.

Testing with a level 15 group.

case SpellType_Mez: {
			if (tar->GetBodyType() != BT_Giant) {
					if(!checked_los) {
						if(!CheckLosFN(tar))
							break;	//cannot see target... we assume that no spell is going to work since we will only be casting detrimental spells in this call
						
						checked_los = true;
					}
					
					botSpell = GetBestBotSpellForMez(this);

					if(botSpell.SpellId == 0)
						break;

					Mob* addMob = GetFirstIncomingMobToMez(this, botSpell);

					if(!addMob){
						Say("!addMob.");
						break;}

					if(!(!addMob->IsImmuneToSpell(botSpell.SpellId, this) && addMob->CanBuffStack(botSpell.SpellId, botLevel, true) >= 0))
						break;
					
					castedSpell = AIDoSpellCast(botSpell.SpellIndex, addMob, botSpell.ManaCost);
			}
			break;
							}
		default: {
			break;
					  }
	}

Did more testing and added a Say("") check where the mez should fire on add and it reaches the say, but no mezzing of any adds.