Perhaps it could be the "sequel" to the first quest, as suggested by Erno?
Or a side-quest even.

And now I have a problem. Programming the tonberry to use a spell is easy enough. HOWEVER, making that spell do damage equal to the total amount of kills is going to annihilate most anything under the sun. And is mostly unprogrammable anyway. SO, my question is thus: How do I program the tonberry to use a spell that reduces the target's health by 10% of the amount of kills made by the target?

Draft graphic ( x3 normal size and gone fuzzy coz of file conversion )

On a more serious note... Perhaps there was an active mine nearby (which would have been hidden from view) which was set off by the first one?
EDIT: Oops, mentioned in first post. My bad.

*points to agi*

chefknife
{
  DefaultSize = 56;
  Possibility = 1;
  WeaponCategory = SMALL_SWORDS;
  DefaultMainVolume = 60;
  DefaultSecondaryVolume = 20;
  BitmapPos = 48, 240;
  FormModifier = 190;
  StrengthModifier = 150;
  Adjective = "pointy";
  NameSingular = "knife";
  MainMaterialConfig == MITHRIL;
  SecondaryMaterialConfig == OCTIRON;
  Roundness = 10;
  Price = 500;
  CanBeCloned = false;
  CanBeMirrored = true;
  Alias == "Chef's Knife";
  AttachedGod = CLEPTIA;
  WieldedBitmapPos = 160, 32;
  EnchantmentPlusChance = 1;
  DamageFlags = SLASH|PIERCE;

  Config BROKEN;
  {
    Possibility = 0;
    BitmapPos = 48, 272;
    Price = 100;
    WieldedBitmapPos = 176, 208;
    EnchantmentPlusChance = 1;
  }
}

everyonesgrudge
{
  DefaultSize = 30;
  Possibility = 100;
  WeaponCategory = BLUNT_WEAPONS;
  DefaultMainVolume = 400;
  StrengthModifier = 50;
  FormModifier = 20;
  Price = 1000;
  BaseEmitation = rgb24(125, 125, 105);
  NameSingular = "Everyone's Grudge";
  MainMaterialConfig == OCTIRON;
  Alias == "say goodbye";
  Roundness = 75;
  CanBeBroken = true;
  BitmapPos = 0, 256;
  WallBitmapPos = 0, 192;
  AttachedGod = LEGIFER;
  WieldedBitmapPos = 160, 160;
} 

tonberry
{
  DefaultArmStrength = 90;
  DefaultLegStrength = 10;
  DefaultDexterity = 5;
  DefaultAgility = 5;
  DefaultEndurance = 20;
  DefaultPerception = 15;
  DefaultIntelligence = 18;
  DefaultWisdom = 18;
  DefaultCharisma = 5;
  DefaultMana = 5;
  SkinColor = rgb16(0, 96, 0);
  EyeColor = rgb16(200, 200, 0);
  ClothColor = rgb16(48, 32, 16);
  HeadBitmapPos = 96, 48;
  TorsoBitmapPos = 32, 112;
  ArmBitmapPos = 64, 144;
  LegBitmapPos = 16, 64;
  TotalVolume = 25000;
  TotalSize = 50;
  NameSingular = "tonberry";
  CanBeGenerated = true;
  Sex = UNDEFINED;
  RightWielded = chefknife;
  LeftWielded = everyonesgrudge;
  KnownCWeaponSkills == SMALL_SWORDS;
  CWeaponSkillHits == 20;
  RightSWeaponSkillHits = 5;
  PanicLevel = 0;
  HostileReplies == "Doink!";
  FriendlyReplies == "@Dd stares blankly at you";
  FleshMaterial = GOBLINOID_FLESH;
  AttachedGod = CRUENTUS;
  WieldedPosition = 0, -2;
}

...And that's just the start.

What needs doing?

Spontaneous Combustion / Critical Existence Failure

I would say it has something to do with the rituals involved, if that's any explanation.