Here's a monster that only works properly using the 1st edition AD&D rules. In that set of rules, anyone can hit this creature on a "natural" roll of 20, with only 5th+ level Fighter-types, 7th+ level Cleric-types, 9th+ level Thief-types, 11th+ level Magic-User-types, or 2HD or greater monsters able to make use of any "to hit" bonuses, due to its unusually high Armor Class. Now, if it is hit, then it immediately dies, thanks to its fixed 1 hit point (treated otherwise as per any creature of less than 1HD). Based on an entry in All the World's Monsters, Volume 1 from Chaosium. The concept could easily be transplanted into another edition, but a harried converter might miss the subtleties involved, especially when translating into 2nd edition rules.
GLASS GOBLIN
FREQUENCY: Very Rare
NO. APPEARING: 4-40
ARMOR CLASS: -4
MOVE: 6”
HIT DICE: 1 hit point
% IN LAIR: 40%
TREASURE TYPE: Individuals K; Lair C
NO. OF ATTACKS: 1
DAMAGE/ATTACK: 1-6 or by weapon
SPECIAL ATTACKS: nil
SPECIAL DEFENSES: nil
MAGIC RESISTANCE: Standard
INTELLIGENCE: Average
ALIGNMENT: Lawful evil
SIZE: S (4’ tall)
PSIONIC ABILITY: nil
Attack/Defense Modes: nil
LEVEL/XP VALUE: II/31
Another goblin affliction similar to nilbogism (see ADVANCED DUNGEONS & DRAGONS FIEND FOLIO – Nilbog), the strange disorder resulting in glass goblins causes most strikes to bounce off of their rigid flesh, but a perfectly-angled attack will cause the glass goblin to shatter into tiny fragments, as if it were truly made of glass. Otherwise, glass goblins live among their normal kin and cannot be told apart from them without touching the glass goblin’s skin (see ADVANCED DUNGEONS & DRAGONS MONSTER MANUAL – Goblin). They live in perpetual fear of bugbears (see ADVANCED DUNGEONS & DRAGONS MONSTER MANUAL – Bugbear), who are the members of goblin society most able to shatter them.
