Thursday, October 15, 2020

RC Hacks & House Rules pg 15: Turning Undead Table

Reviving these old Rules Cyclopedia posts to talk a little bit about a resolution system I’ve been intrigued by for a while now. Even though this is ostensibly a Rules Cyclopedia hack/house rule, it is naturally applicable to B/X and OSE as well.

On this page we have the table that a Cleric consults for Turning Undead. Specifically, I’ve been recently interested in Repurposing the Cleric’s Turn Undead Matrix for resolving various other tasks like “Thief Special Abilities” (I’ve discussed these in the past here). It can also be used to supplant the “Optional Ability Score Check” form of resolution for other tasks, which while convenient, is a crutch I have never particularly enjoyed employing for a variety of reasons.

Here is a quick simplified reproduction to refamiliarize you with how the table works (I’ve never been too fond of how the Rules Cyclopedia swaps the axes, and how it provides named Undead instead of HD...but I suppose that’s a nice way to telegraph some setting if you squint at it):

While not as robust or simple as the sainted Saving Rolls in Tunnels & Trolls (first universal task resolution system in an RPG!) because of the table lookup, I still think the Turning Undead Matrix checks a lot of my boxes for Task Resolution. Let us go over a few of these advantages first:

  • It accounts for Character Level
    • The often used “Optional Ability Score Check” relies on Scores that do not strictly improve in most games and is usually just a simple roll under for pass/fail. This ties competency to one of the first six rolls players make to play the game during Character Generation and I’ve always felt it unduly punishes those with low scores but sufficient Player Skill to advance in level.
  • It accounts for Task Difficulty
    • The “Optional Ability Score Check” usually has to be modified via ad hoc fiat for this (giving a “bonus” to the roll in the form of a negative number or increasing the ability score for the purposes of the roll), just as Thief Special Abilities sometimes receive that “circumstantial bonus” for a Rusty/Shoddy Lock.
    • With the Turn Undead table, there is a clear progression. Some Undead woefully outclass the Cleric at first, but with each level gained, new opportunities become available, and prior threats soon become trivial.
  • Rolling High Is Good
    • Both the “Optional Ability Check” and Thief Special Abilities rely on a Roll Under comparison for resolution, while many other conventions in the rules incentivize the player’s rolling higher for better results. I’m not fanatical for this kind of symmetry in the rules, but the momentary cognitive whiplash of having to parse a “natural 20” as “bad” frustrates some players.
  • It isn’t as “Swingy” in terms of probability (ie: it leverages the 2d6 Bell Curve distribution instead of a single d20 or d100 roll)
    • This makes median results appear more common over time (which does wonders for assuming default competency with tasks). There is seldom anything as de-protagonizing as that persistent 5% chance of a “20” on a Roll Under Check. Even with the highest natural Ability Score of 18, failing 10% of the time isn’t really reassuring.
  • It features “Degrees of Success” that are not really present outside of a few other places (such as the Reaction Roll, which is probably a close cousin to this table)
    • T for “automatic Turn” and D for “automatic Destroy” result in different outcomes, producing different situations in play.
    • Ability Score Checks/d100 Thief Special Abilities are normally a binary pass/fail.
  • It places Dice in the Player’s Hands
    • Some Thief Special Abilities are often rolled by the DM (Hear Noise, Find Traps, Move Silently, Hide In Shadows) because the results of the die roll can immediately dictate success/failure based on percentage chances or interfere with strategy (“Just because I didn’t find any traps...doesn’t mean there aren’t” etc. )
    • With the “Hazard Difficulty Level” obfuscated, the Player can still roll, while the DM consults the matrix for resolution. This is closer to the To-Hit/AC Comparison so it supports this kind of hidden information, but more importantly it doesn’t force players to witness their failure in real time, and creates an opportunity for narrated consequences rather than immediate assumptions of failure.
  • It allows the Character to Attempt things outside of their normal Level
    • A First Level Cleric can attempt to turn 2d6 Ghouls (2* HD Monsters with a very powerful and potentially devastating Special Ability) although these chances are somewhat slim (only an 8.34% chance of rolling 11+ on the 2d6) this could easily circumvent a nearly certain TPK at lower levels.
    • This incentivizes trying things that might seem out of a Character’s Scope, and I always like to encourage that.
  • Two Dice Rolled provide interesting opportunities for grafting on additional sub-systems/deriving metadata or repurposing the roll:
    • Doubles can have significance, both for “successful” doubles and “unsuccessful” doubles. This could even mandate a 2d6 roll on the automatic “T” and “D” results if you wish.
    • The highest or lowest result can be used on a simple d6 table
    • They could even be read as a d66 for an additional 36 entry table look up

So, with all these features available to us, how can we leverage the Cleric’s Turning Matrix for some Task Resolution outside of dealing with Undead? Here are some ideas:

Thief Special Abilities:

HD can be very easily re-contextualized as “Hazard Difficulty” in addition to the more common definition of “Hit Dice.” When establishing a Hazard Difficulty via fiat is not preferred or is not immediately apparent based on the fiction, one simple way to do so would be to use “level of the Dungeon” for Thief Special Abilities with a static/inanimate target (Open Locks, Find Traps, Remove Traps, etc.) or even “HD of Foe” for others that directly target a living creature (like Pick Pockets/Move Silently).

Example: A 1st Level Thief wishes to Open A Locked Dungeon Door. They have descended to the second level of the dungeon (base Hazard Difficulty 2), so a 9+ is needed on 2d6.

This does mean that a 1st level Thief travelling to the 4th level of a dungeon will be facing some pretty insurmountable odds by default (although see below for some ways to allow for players to make decisions that address this by lowering Hazard Difficulty), but this does have the side effect of telegraphing danger directly, and even emphasizing the need for caution when exploring a dangerous new area.

Let us go through the Thief Special Abilities to see how this could work. Keep in mind that I only engage a resolution mechanism for these whenever the outcome would be interesting, and failure has consequences. An example I often use is that any Thief worth their salt, given the proper tools and enough time would be able to Open just about any nonmagical lock under ideal conditions, but these kinds of conditions are seldom found in the Mythic Underworld/Adventure Environment.

Open Locks: Level of Dungeon/Threat is a good way to establish initial Hazard Difficulty here, potentially adjusting it upward/downward for particularly complex/simple locks as necessary. I generally rule that Opening A Lock takes at least 1 Turn of activity on average and rolling above the number or achieving the T result on the Matrix means the Lock opens in 1 Turn (~10 minutes). For a D, this could be Hazard Difficulty in Rounds as deft, experienced hands swiftly guide their tools to the appropriate tumblers.

Have particularly perfect Tools? Lower Hazard Difficulty. Wish to take more time on a tricky (re: Higher Level lock), each additional Turn spent lowers the Hazard Difficulty for your roll by 1 (remember to check for those Wandering Monsters). Locked doors become much less of a barrier to exploring the environment with this system, but they consume resources in the form of Time with its associated Encounter Risk. Doubles on Failure could indicate Loss of a Lockpick/Tool, jammed lock. Successful doubles: reduce the duration to 1 round.

Find Traps: Level of Dungeon/Threat can again serve to establish initial Hazard Difficulty. Similar durations to above, and more time spent carefully investigating could reduce the target. With these “Detection” based Thief Abilities (this, and Hear Noise), there has to be something there to find, naturally, and to address the ponderous “constantly searching” problem I tend to allow those “D” results to just outright reveal traps of corresponding Threat as they’re encountered (a “Level 1 - Barely concealed Trip Wire” is completely obvious to a Footpad (2nd level Thief). It’s usually the consequences of interacting with the Trap or it’s Triggers that create the interesting situation, not the de-protagonizing “Gotcha! Please make a Saving Throw!”

Remove Traps: Level of Dungeon/Threat again for initial difficulty. Similar durations to above, and more time spent carefully investigating the Trap/Triggers could potentially reduce this. Here we can leverage the 2d6 die roll in interesting ways in the event of Success/Failure if we wish to add some additional tension. Rather than just “springing the Trap” on Failure, perhaps it only springs if Failure and Doubles are rolled. Doubles on a “successful” roll could provide the Thief with the ability to subvert/repurpose the triggering conditions of the Traps.

Climb Walls: Much like Open Locks, given enough time, adequate tools, and ideal conditions Climbing is not normally something I’d require a roll to adjudicate. It’s only when these criteria aren’t met (vertically fleeing from crossbow wielding Bugbears, cascading slicks of ichor and damp, insufficient rope, etc.) that I’d look to the dice to resolve an ascent or descent. Taking additional time to “size up” the climb, secure ropes/tools, or “go carefully” etc. could reduce difficulty. A “D” could result in less time to scale the obstacle. Initial Hazard Difficulty can be based on the height here, perhaps increasing by 1 for every 20 feet.

Move Silently: As a Thief Special Ability with a “target” the HD of the target could easily serve as the default Hazard Difficulty (and this could be increased by a floor strewn with dead leaves or other such challenging conditions for Stealth). Distracted targets might lower the difficulty. Multiple Targets could be additive, or an Average of the HD could be used to establish this baseline difficulty. Particularly oblivious or attentive targets might see a modification here. Since this is usually used in conjunction with Surprise Chances or Evasion, D results could further improve these odds.

Hide In Shadows: Similar to Move Silently. Suboptimal lighting conditions could increase difficulty.

Pick Pockets: Target Hit Dice establishes Hazard Difficulty. If you are feeling lazy the sum of the 2d6 results could easily be the amount of coin pilfered.

Hear Noise: Perceivable Noise could be considered a “static” target (similar to Find Traps, there has to be a Noise To Hear), so conditions are important for establishing difficulty, but baseline Dungeon Level can work if there are no mitigating circumstances. The duration for listening is often handwaved as instantaneous, but I think the 1 Turn default (with decreases for D results) could also apply here, as could the “spend more time to lower difficulty” option. The longer you listen, the more likely it is that you hear something useful.

Taking a cue from my previous post on Thief Abilities, it could even be possible for Thieves to “Specialize” (treating them as a level higher for certain things, in exchange for being a level lower at others). I always liked the idea of a Master Pickpocket who focused his studies on that branch of thievery and wouldn’t dream of futzing with a Locked Door. Another option would be to increase the die type (d8) for Specialization.

This covers the standard Thief Special Abilities found in the earlier editions and clones, but let’s not let the Other standard Classes languish. How could this table be used for some of the things these Classes get up to?

Fighters: Need to adjudicate a Disarming attempt? Foe Hit Dice as Hazard Difficulty. Failing Doubles could cost you your armament, while doubles on success could sunder a foe’s weapon! Grappling/Tripping and other Combat Maneuvers could be likewise handled in this fashion. I’m sure that “T” and “D” results (and failing/succeeding doubles) could be reskinned into conditions imposed by Wrestling by someone appropriately inclined.

Magic-Users: Need to identify a Spell or Magical Effect? Level of Spell for Hazard Difficulty (Higher Level M-Us immediately identify the magics of the lowest orders...and maybe on a “D” they gain additional insight into the Caster?) Want to eliminate the tiresome tax of Read Magic for Scrolls? Level of Spell as Hazard Difficulty (some magics might be beyond the caster, but it does provide an option for a little bit of Over-casting...and chance of more interesting Failure/Fizzles than normal).

Need to resolve Ritual Casting? Use the “One Turn per Hazard Difficulty Level” rule, if you rush the Difficulty goes up...reduce it by taking more time/consuming expensive components/reagents, etc.

I have seen “Roll To Cast” systems utilize matrices like this before as well, which could be interestingly fiddly as a way of supplanting standard Vancian Magic (I do love the idea of being able to riskily “Overcast” higher level spells at lower levels). Doubles on Failure could indicate damage in addition to other consequences (you could sum, or more compassionately just use one of the die results). I don’t see it being too onerous as the “T” result eventually translate to an automatic success for lower level Magics. Perhaps “D” could adjust any variable parameters upward/affect more targets/provide additional benefit?

The Turn Undead Matrix could also be a good option for a desperate Caster to try to cast a Spell when their allotted slots are used, but I’d make sure that drastic consequences exist in the event of failure, and that some cost is required even with a “T” or a “D.” Again, we could leverage the results of the 2d6 or whip up a nifty d66 table with all sorts of lovely consequences (see TROIKAs Oops! Table for something handy).

Some of these options could also find their way to the Demi-Human Classes as well if you wish, or you could even implement it for resolving other common tasks: Foraging for Food (HD as Number of People You Need To Feed), Abstracting Evasion/Chases, or even crafting an Item.

Have any interesting ideas for Tasks that could benefit from the Turn Undead Matrix for resolution? Let me know!


  1. Okay I love this. I've been thinking of adopting the Specialist rules from LotFP for OSE to streamline those thief abilities, but I like this a lot better. I think you could replace any kind of X-in-6 roll with this system. You get to keep the "rolling high is good" feeling while also streamlining challenges so they all use the same system, at least outside of combat. Sustained use will probably reduce the need to actually reference the table too. All it needs is some kind of alternate value for T and D that make sense outside of turning undead and bam!

    1. Glad you like it! I agree that it has a lot going for it and might expand upon it a little later in future posts. "T" as Success and "D" as Success + Benefit are really just the most basic gloss (T for "Triumph" and "D" for "Dividend" maybe?), and I think an interesting goal for Thieves in general should be to get the Odds in their favor enough to "not require the roll" (ie: find a way to reduce that Hazard Difficulty through Clever Play, so that they reach the wonderful "T" result and not leave things up to chance).

  2. This is great! I’ve been fiddling with a 2d6 table more along the lines of the Monster Reaction Table (which, I note, you mentioned) but this feels more satisfying to me.

    My own house rules fall somewhere between B/X and Knave (Ability Bonuses are larger and play a more prominent roll in things). I’m curious how I might adapt this to a 1st level cleric who is adding a +2 or +3 to their checks. I suppose i could base skills/turning on level and continue using Ability mods strictly for saves (I don’t disconnect the save mechanics from the Abilities).

    Very interesting food for thought!

    1. Glad you've found it interesting! A +2 or +3 bonus on a 2d6 will certainly un-ring the Bell Curve pretty significantly (moving those medium results upward, and with the 7, 9, 11 thresholds, if it governs all tasks it will certainly lead to more successful results). In older versions of D&D the Charisma Mod is handled with different bonuses than the other Scores for precisely this reason (because it is used with the Reaction Roll table). If Scores don't modify the "Check" but instead the Effective Character Level for specific tasks, you might get some interesting things out of that (although some DMs season power-level to taste, and that will lead to some pretty dramatic competency with lower level Hazards resolved with this system). For Cleric's specifically, you could probably apply the bonus to the "number of Undead affected" roll without a major shift.



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