18 Rules You May Have Missed in Old-School Essentials
Wandering monsters, traps, equipment, climbing, magic, and more.
This is a follow-up to my previous post about Old-School Essentials rules.
I’ve been playing Old-School Essentials for a few years but from time to time I still notice rules I missed on previous passes. Or rules that I forgot between reading them and the following session. Many of these are relevant to particular kinds of situations and it might not make sense to apply them as written outside of those cases. I don’t advocate being a stickler for all of these rules, only to spend a moment considering what they might add to the game. You might realize that one of these addresses a problem or question you run into during play, one that you didn't realize the rules provided an answer to.
Rules from Old-School Essentials
The first four rules are referee-facing, although players may wish to be aware of them. The rest are both player- and referee-facing. My house rules or interpretations are in parenthesis.
The chance of encountering wandering monsters may increase if the party is loud or carries bright lights. What counts as a bright light? Does a torch? A standard lantern? A bullseye lantern (in Carcass Crawler 3)? Presumably not a candle. (I feel this is most appropriate in spacious environments rather than cramped twisting ones. The text says noise and bright lights can increase the chance, as opposed to the frequency, of wandering monsters, so I interpret this as increasing a 1-in-6 chance to a 2-in-6 chance, or 3-in-6 in extreme circumstances.)
Wandering monsters in a dungeon are encountered moving toward the party (at least by default). They can still be surprised so the implication is they were moving toward the party before they detected the party.
Parties carrying light sources in otherwise dark areas cannot surprise other creatures, but may still be surprised by them. (Creatures without vision or the ability to sense heat at a distance can still be surprised. A door might block enough light so that a party opening it still has a chance of surprising those inside.)
Traps only have a 2-in-6 chance of springing when a character triggers them. (This rule makes some traps more dangerous, since the they may not trigger until a few characters are in a trapped area. Personally, I think a trap’s chance of springing should depend on the specific workings of the trap, the expertise of its construction, and the condition that time has left it in. But 2-in-6 is a good baseline especially for traps found in ruins or set by amateurish trap makers or under circumstances of scarce materials or time.)
The AC bonus gained from using a shield does not apply to attacks from behind. (A rule with minimal impact, but thieves attempting to backstab will appreciate it.) When retreating from melee (as opposed to making a fighting withdrawal), the shield bonus does not apply, as one’s back is turned to attacks.
Characters wielding slow weapons such as battle axes and crossbows act last during each round of combat, after all sides have gone. (I usually ignore this property since I find it slows down combat with little upside.)
Dousing an opponent with a splash weapon like holy water or burning oil only applies damage for two rounds of combat (20 seconds) before the remaining liquid drips off. A 3’ diameter pool of oil burns for 1 turn if lit. Before I noticed this, I let monsters doused in oil burn for longer than two rounds, but I prefer this rule.
Using a tinder box to light a fire, such as igniting oil or a torch, requires one round per attempt and only has a 2-in-6 chance of success each try. I like the tension this brings to combat. It also encourages multiple characters to make the attempt if the need for fire is urgent.
Standard rope may only hold the weight of 3 people and their equipment. If that doesn’t seem like much, keep in mind standard rope represents lightweight rope made with common medieval technologies, rather than the heavy-duty rope used on a ship or in a siege weapon or modern rope. The referee could introduce superior rope with greater strength, less available than common rope.
Any character may attempt to climb a ladder, rope, or steep cliff (but not a sheer cliff) under stressful circumstances by rolling a DEX check. Without stressful conditions, no roll is necessary. Only a thief (or a member of another classes with the climb sheer surfaces skill) may attempt to climb very steep or sheer surfaces without specialized equipment.
A thief may only roll once each to find a treasure trap, to remove it, to understand a non-magical text or code, or to open a lock (at least until they gain a level).
In order to cast the reversed form of a spell, an arcane spell caster must memorize the spell in that form. An arcane caster may not decide to cast a spell in its reversed form on the fly. (Ignoring this rule probably won't hurt gameplay and is a small act of defiance against Vancian casting.)
Divine spell casters serving lawful deities can incur deity disfavor for using spells in reversed form (for example, cause fear is the reverse of remove fear). Spell casters serving chaotic deities may only use non-reversed forms of spells to help allies of their religion. Using these non-reversed spells in other circumstances risks deity disfavor. An individual neutral deity either acts like a lawful deity or like chaotic deity in this regard, depending on the tendencies of the god in question. (I can imagine a lawful god wanting to cause fear in some instances and other exceptions. It might be worth considering each spell on a case by case basis.)
Stowing treasure or other items in a backpack or sack requires 1 turn (a turn represents 10 minutes). Packing an additional item without unbalancing a hiking pack can require reorganizing the pack, so this isn't unreasonable. And its one more way to increase time pressure in a dungeon.
Drinking a dose of a potion requires one round during combat.
The referee rolls to determine how long the effect of a magic potion lasts and keeps that information secret from the player. The referee tracks when the potion’s effect wears off. (I suggest marking when potions run out on your dungeon turn tracker.)
When a character is slain by destructive magic or effects, any equipment they carry is destroyed. The referee may allow magic items a saving throw using the slain character’s saving throw values plus any bonuses the item might have. (House rule: I might allow especially durable items like maces or iron spikes to remain intact. If you’re using a house rule where a character doesn’t automatically die at 0 hit points, I’d still consider whether equipment is destroyed by the attack that drops the character to 0. This brings additional costs to being downed, even if the character manages to survive. You could also assign numbers to each row of gear on the item-based encumbrance character sheet and turn it into a random table to determine which items are destroyed.)
Retainer loyalty checks are made when the retainer is faced with great peril during an adventure (on a failure, they run from the danger) and after any adventure (if they fail, they stop working for the PC). (This may seem like it will lead to excessive turnover of retainers but retainers with higher loyalty, as a result of PC actions, have a much lower chance of failing loyalty checks.)
Unanswered questions.
Even after playing Old-School Essentials for a few years, I still haven’t found answers to a couple questions, at least not in the rules themselves:
How do you apply the brace property of polearms and spears in practice? Under what circumstances does it come into effect? Without a charge rule and a ready action rule, it’s unclear to me. That hasn't stopped players from using it when it fits the scene.
How long must spell casters sleep before they may memorize their spells? Six hours? Eight? This doesn’t usually matter but I’ve seen the question arise in play a couple times, when we were counting the hours. The rules are clear spell casters require an additional hour to memorize spells, once their night’s rest is completed.
Did you miss any other rules on your first passes through the rulebook, only to discover them later?
For an example of OSE play, check out this mostly rules-as-written solo playthrough of B1 In Search of the Unknown.
Very cool!