A is also for ADVENTURERS
Rival adventuring parties usually have a leader plus 1d6 additional members. Whenever the player characters encounter a rival party, there is a cumulative 2-in-6 chance per party that they've re-encountered a rival they've met before. (As a result, there are never more than three rival teams at one time, but if one team dies...)
When first encountered, each member of a rival party is a random level. Roll 1d12: 1 Two levels lower than player characters, 2-3 One level lower than player characters, 4-9 Same level as player characters, 10-11 One level higher than player characters, 12 Two levels higher than player characters. Each time a rival party is re-encountered, there is a flat 1-in-12 chance that they've leveled up since the last encounter.
When determining reactions, roll 2d6, modified by Charisma: 2 worst, 3-6 bad, 7-11 good, 12 best. (Reactions are listed in best-to-worst order below for added inconvenience.)
Random Rival Adventuring Parties
1 A fantastically wealthy and idiotically foppish 0th-level dilettante is escorted through the underworld by a hyper-competent team of seasoned adventurers he's hired as "porters" and "torch-bearers" to show him around.
2 Handsome but generally clueless and romantically oblivious young man followed by entourage of wide-eyed and exceptionally talented young women in a variety of military and school uniforms who are obviously in love with him. The women will consider any female player characters or retainers to be dangerous rivals for the young man's affection, but some of them might develop competing crushes on a high-Charisma male character or retainer. Despite his general obliviousness, the young man is an unbelievably effective monster hunter, capable of hitting seemingly invulnerable opponents for massive amounts of damage.
3 A genius inventor leads his extended family of plucky adventurers. There's a cumulative 1-in-12 chance each per encounter that they've been transformed into anthropomorphic ducks by an experiment gone wrong. Each time they're encountered, they're out testing a new invention and insist on demonstrating it to/on the player characters. Depending on the reaction roll, the invention might be beneficial to the test subject, a random piece of anti-diluvean technology that the inventor will offer to sell to the player characters because he considers it a failure due to its lack of originality, completely ineffectual, or a dangerous weapon. (The inventor and his family are always friendly and affable - the reaction roll merely determines what kind of device they are friendly and affably trying to test on the player characters.)
4 A family of master criminals wearing black-and-white striped jumpsuits and black domino masks. Depending on the reaction roll, they might ask the characters to hold some treasure for them "until the heat dies down", open some locked doors and disarm some traps for the player characters as a demonstration of their skill, ask the player characters to join them on a "heist" before inevitably betraying them, or target the characters for a stick-up. When unloading goods from the characters during a betrayal or stick-up robbery, the criminals will prove to be far more interested in one random type of mundane object than in coinage or other treasure.
5 A team of adorable woodland creatures with whimsical names bearing miniature adventuring gear made from twigs, leaves, and acorns. They tend to like druids and elves and to dislike any other "giants" they encounter. Each time they're encountered, they're on a "mission" to rescue the victim of a kidnapping. Depending on the reaction roll, they might ask the player characters for help, attempt to detain them for questioning, believe that the characters are trying to thwart their rescue, or believe that one random character is the "victim" and attempt to return them to the nearest city the next time the party is asleep. They prefer to lay traps (pits, snares, deadfalls) and ambush the characters in their sleep rather than initiating direct combat. They have few hit points, but are hard to hit due to their small size and use of cover.
6 A hyper-intelligent talking dog leads a team of under-qualified amateur detectives. Each time they're encountered, they're searching for "clues" to solve a mystery. Depending on the reaction roll, they might ask the player characters for help, attempt to detain them for questioning, demand random items of mundane equipment as "clues", or be certain that the characters are guilty of the crime at the center of their "mystery".
7 A team of outcast mutant superheroes. Each has a garish spandex costume, a silly code-name, and a single MAGIC power they can use at will. Each time they're encountered, they're on a new "mission" to defeat a different "villain". Depending on the reaction roll, they might see the player characters as potential victims in need of protecting, as potential allies in their fight, as an unnecessary distraction from their "mission", or as their "villain" of the week.
8 Self-aggrandizing and belligerent "captain" wearing a yellow jumpsuit is accompanied by 1d3-1 intelligent and reasonable scientist advisors in blue jumpsuits and 1d12+1 security personnel in red jumpsuits. A reaction roll is only possible if advisors are present, otherwise the "captain" is unerringly hostile. The security personnel have only 1 hit point each and are incompetent combatants. When they're all defeated, the "captain" will teleport to safety. He always possesses a random piece of anti-diluvean technology that he drops on any roll of natural 1.
9 Mysterious figure in a space suit leads a team of technicolor plant- and fungus-humanoids. If the player character have lost a character or retainer to olive slime, purple moss, russet mold, or the like, that character's transformed body will definitely be present. Depending on the reaction roll, the figure may be willing to trade unique MATERIAL COMPONENTS for a proprietary medicine that cures the effects of such transformative threats, or may attempt to "recruit" player characters by transforming them.
10 A bright yellow giant is accompanied by technicolor spectral undead. If a player character or retainer has recently died, they will definitely be present. The giant is insane, always hungry, and utterly paranoid about the "ghosts" he claims follow him everywhere. Depending on the reaction roll, he may believe the player characters are "ghosts" and be terrified of them, warn the characters about the nearest actual undead threat, demand to eat all the characters' rations, or believe himself to be temporarily invulnerable and attempt to eat the player characters whole.
11 An angsty human barbarian with a random magic SWORD leads a group of half-animal, half-mineral monsters. Each creature has a natural attack that mimics the effect of a random spell, and makes a single weird alien sound that is nonetheless intelligible as conversation to the barbarian. He is determined to slay any "evil wizards" and destroy an "unholy magic items" he encounters, with predictable results for the player characters.
12 An undead anti-cleric with the power to "turn" living humans leads a party of undead crusaders to recover unholy relics for the glory of Hell. If a player character or retainer has recently died, they will definitely be present. The crusaders will demand the destruction of any holy symbols or divine magic items the characters posses, and will attempt to "convert" living characters and "recruit" recently dead ones to their anti-religion. Happily, they are also eager to trade to acquire any CURSED items in the characters' possession.