Some explanations about how to make heavy armor feel different than just being good at dodging attacks.
Playing Dodgeball in Plate Armor
What even is armor class in D&D? Imagine two characters: one is the most dexterous rogue who ever picked a pocket wearing studded leather armor, the other is a brawny paladin with muscle for brains wearing 55 pounds of chain mail armor and carrying a steel shield. Imagine yourself swinging a sword at either of these archetypal figures. The rogue is likely to dodge out of the way of your attack while the paladin would stand there and let their chain mail or shield soak up the hit, leaving themselves relatively unscathed. Now, how is this represented in the mechanics of D&D 5e? Why, these two are identical, of course! The rogue’s deft dodgery and the the paladin’s stalwart steel are both represented, via a very simple math problem, as a 17 armor class.
It is a common notion that when someone begins the journey of morphing their starting point of D&D into their ending point of their eventual fantasy heartbreaker, the first victim is often D&D’s Vancian spell slot system, in favor of a spell points system. For a brief history lesson on this point, in APA-L (meaning the Amateur Press Association for the Los Angeles Science Fantasy Society, a fan-newsletter the then-equivalent of blogging, frankly) issue #522, dated May 15, 1975, one John Hertz would suggest using spell points. (This was also the issue where we see the first house rules for critical hits and fumbles, which is now a core part of the D&D experience.) I naturally have come up with my own rules for casting spells that aren't dissimilar from a spell point based system, although sans any spell list, as all who make heartbreakers must do. But if I had my pick for the one set of rules that begs for a newly houseruled system, it would be D&D’s armor class system that barely differs, if it does at all, between the harm-avoidance gained by being dexterous and the harm-avoidance gained by wearing a heap of metal. And that is before you consider the fact that, as my colleague Ava of the Permanent Cranial Damage blog suggests, “AC isn't AC: it's just a hidden pool of HP, masquerading as something else.”
Into the Odd and its descendants (by the way, if you are reading this and weren’t aware, Cairn is a hack of Into the Odd and not vice versa. Lol, lmao even) have a clever way of distinguishing these two aspects. Hit Protection represents many things one of which is dodging out of the way of an attack. Whereas Armor is damage reduction against each attack, even when you hit points have run out. As Ava states in the aforementioned post, “mechanics like Armour in Into the Odd are a little better [than traditional Armor Class] in that they represent an ancillary pool of hit points with a slightly different mathematical function in a clearer way”. However, my issue with Oddlikes is purely that I essentially am looking to create a game with more to sink your teeth into. My position is always that Into the Odd (and Cairn, Mausritter, etc.) already do what I would like for a rules-light game. There is only one direction left to go: heavier.
Being armored and being dodgy each present benefits for damage avoidance in Prismatic Wasteland, but these benefits are functionally different. (By the way, the current very-much-WIP rules for Prismatic Wasteland recently went up on my Patreon for all patrons, if you want to dig into the full thing. I recently realized that many readers of the blog don’t know that Prismatic Wasteland isn’t just a famous blog and luxury lifestyle brand but is also a forthcoming game system.) Of course, all damage avoidance avenues ultimately boil down to the same thing (prolonging your life when a bear swinging a mace is trying to kill you), but the way they lead to avoiding death can still have a different gamefeel from each other.
Dodge, Duck, Dip, Dive, and Dodge
Dodging is more of an active choice than wearing armor. When you are wearing armor, you can mostly stand there and benefit from the armor. For dodging attacks, you are the one that has to do the dodging. Video games (especially Soulslikes, where the art of dodging is the difference between life and death) have done a better job modeling this than tabletop roleplaying games typically have. A passive modifier to your armor class doesn’t feel like making any active choices.
First, to make choices meaningful, you have to give information. The referee needs to describe the enemies and the way they attacks, differentiating the heavy hitters from the skirmishers, for the players to know when it is important to dip out of the way and when they can just stand their ground. One tool I use for particularly deadly attacks is the telegraph. No, not the invention, but a signal in one turn that the enemy is about to do something deadly. If you want your dragon to breathe fire down on the party on the next round, describe it as breathing in deeply the turn before. Give them a chance to realize what is going on and you don’t need to water down the fire breath. Prismatic Wasteland monsters are going to have some mechanical support to this method, but it is something to put into your GM toolbox that you can implement with any system.
There are two ways to model dodging in Prismatic Wasteland, and each has different costs. On the front end, if a PC suspects they are about to be targeted by deadly attacks, they can take the “Avoid” action, which imposes Disadvantage on all attacks against them. The only cost to this is one of your actions (you have 1 to 3 per turn, depending on how initiative goes for you). In practice, this action is mostly taken when you have a feeling you are about to get waylaid by something powerful.
But there is another avenue for dodging once you know, not just suspect, that you are getting waylaid. Before the opponent makes their attack against you but after they declare it, you can spend some of your Dexterity (all stats in Prismatic Wasteland double as a renewable resource pool) to dodge out of the way. This is more powerful than the Avoid action, since you are still getting hit with avoidance but just making the hit less deadly by imposing Disadvantage. With the Dodge reaction, you are entirely jumping out of the way of the attack. However, spending Dexterity is nothing to sneeze at. If you are heavily armored, the cost to dodge is 3 Dexterity, a hefty amount when all stats in Prismatic Wasteland max out at 12. If you wear medium armor, the cost goes to 2 Dexterity and if you are lightly armored or wearing no armor at all the cost is 1 Dexterity. The Dodge reaction therefore benefits both characters with high Dexterity scores and who are wearing little to no armor. Our stealthy rogue from earlier can dodge out of the way of 11 attacks before going down to 0 Dexterity, while our bulky paladin with a completely average Dexterity (6) can only do so twice. A big difference in how these characters avoid damage!
The Benefits of Being a Tincan
But when the stealthy rogue does get hit, it hurts more than when the bulky paladin gets hit. Prismatic Wasteland flipped the Into the Odd formula of only damage: there is a to-hit roll instead of a damage roll. You already read me toying with this idea last year. But that isn’t exactly right either. Essentially each weapon has a random but persistent damage amount that is determined when it is first obtained, which is the “damage roll”, but this is rolled when the weapon is obtained, not during combat. And the to-hit roll doesn’t actually determine whether you deal damage, but how much damage you deal. On a full success, you deal your weapon’s damage. On a partial success, you deal your weapon’s damage minus the defender’s armor value (but at least 1 damage), and on a failure you just deal 1 damage no matter the weapon. The attack roll is a typical attribute test where you seek to roll under your attribute to succeed. There is also a difficulty score that you must roll above which determines whether that success is full or partial.
Armor has two passive benefits that factor into an attack. First it is the difficulty score for the attack, which increases the odds the attack is a partial success instead of a full success (it has no impact on the odds of a failure). And then if it is a partial success, it reduces the damage of the attack. This represents the heavily-armored paladin standing stalwart in the face of violence, getting hit but the armor dampening the effectiveness of those hits (but not entirely). Aside from power armor and other magic-armor-equivalents, armor typically provides a defense value between 1 and 5. Let’s say our example paladin has a defense of 4. That means a +33% chance of turning a successful attack into a partially successful attack which reduces that attack by 4. I’m not a big math guy, but I think that is the equivalent of like a 1.33 Armor for an Into the Odd type system.
But in Prismatic Wasteland, even armor has an active component. One of the many, many things I liked about Errant is that using your armor is an active choice. As Ava talks about in this post on the subject, armor provides blocks that can be used to deflect an attack. Armor in Prismatic Wasteland has a similar function. Almost all items in Prismatic Wasteland have a four-segment clock next to them that tracks either how much a breakable item has degraded or how much of a consumable item has been used. With armor, there are certain weapons (mostly ones that smash) that, on a critical hit, damage armor. Each time armor is damaged, it fills in one of the segments on its clock. When all four are filled it, the armor no longer provides any benefit until it is repaired.
When a character wearing armor is attacked, they can choose to absorb more of the blow with their armor. When they do so, they fill in a segment of their armor and subtract their armor’s defense value from the attack’s damage (regardless or whether it was a success, partial success, or even a failure). They can also choose to fill in more than one segment to really lean helmet-first into the attack, soaking more of the damage by damaging their armor further.
Shields only have the active benefit of armor. They don’t increase the wielder’s defense, so don’t impact the difficulty score for an attack or reduce damage on a partially successful attack. Instead, like the famous Shields Shall Be Splintered rule that Trollsmyth proposed at the dawn of the OSR in 2008 (which has its critics to this day) it can be used as ablative armor. When the shield-bearer is hit with an attack, they can fill in a segment on the shield to reduce the damage by 1d6. Fill in two segments and it reduces the damage by 2d6, etc. Deciding to fill in all the segments at once reduces 4d6 damage, which would negate the damage from all but the most powerful attacks, the equivalent of holding it up to block dragon fire. Also, if you roll a natural 6 on the d6, you don’t have to fill the segment. This last part is essential, as it makes the shield feel more like a reusable tool and is less likely to lead to what Temporal Negativity called “rules [that would] lead to characters carrying as many backup shields as they can, which is ridiculous”.
Back to our two hypothetical characters, the sneaky rogue is wearing pretty good light armor, giving them a defense of 2, while the bulky paladin has heavy armor giving a defense of 4 and a shield. The paladin has a 16% higher chance of turning a full success into a partial success and when those partial successes happen, reduces damage by 4 instead of 2 for the rogue. Both characters can choose to absorb more damage with their armor, but it's twice as effective for the paladin. Regardless of the success of the attack, the paladin can also reduce the damage by 1d6 per segment on their shield.
The rogue and paladin each have successful methods for increasing their odds of surviving an attack but now the gamefeel differs depending on which type of character you are playing. The rogue is more attuned to whether an attack might be dangerous and, when they think a powerful attack is coming, spends their limited Dexterity resource to jump out of the way. This is a bit more like gambling because with the Avoid action, you may not get hit (although taking this action basically makes it less likely to be targeted, which is its own advantage) and you have to spend your Dexterity before you even know how deadly the attack might be. The paladin’s armor is more passive, but not entirely so, and their armor and shield are separate resources that must be managed and repaired between fights. There is much more to it than just giving both characters a 17 Armor Class and calling it a day.