Originally published at: Introducing New Monster Mechanics — Errata — Advanced Old School Revival — OSR+
What better way to celebrate Christmas than to introduce some cutting edge new mechanics, fresh from the upcoming OSR+ Bestiary!
Note: These mechanics are still undergoing testing, but derive from the upcoming Bestiary, which features 300+ monsters and hundreds of new abilities unique to monsters.
Okay, here's the skinny:
Banes & Boons
We use banes and boons instead of the "resistances" and "immunities" that appear in traditional RPGs to ensure that something always happens in the fiction even when a PC's efforts are thwarted by the monster's passive abilities. A dragon may be totally immune to fire, but what happens when someone tries to hit it with a fire-based attack? We could say that nothing happens, but that's not interesting, and it's often frustrating for the player to waste their turn in this way. Instead, we could say that a fire attack taunts the dragon, because the monster is amused that the puny adventurer dares to attack it with the one element it's totally immune to: the taunts reaction would then force the dragon to spend its next action targeting that puny adventurer. In effect, the PC's attack was ineffective, but the state of the fiction changed, because now the dragon is focused on the PC.
Monster Reactions
When a monster is subject to a peril of a particular type, it automatically responds with one of 12 standard reactions. These reactions describe what happens either:
- When the monster is subject to the peril, or:
- Instead of the monster being subject to the peril.
Using our fire dragon example above, we might say:
Fire
... to indicate that the monster is taunted by fire.
Monster Phases
Phases are actions that get automatically triggered when a monster has a certain status effect. A phase always specifies a condition and an ability that triggers on that condition. For example:
Rage (Bloodied). The monster enters a berserker rage, which lasts for the duration of the scene. While enraged, if damage would kill the monster, the monster makes an escalating Mighty check (TN 11) to remain conscious. While berserk, the monster will not stop attacking its foes, even if its life is in danger, and the berserker rage will only end when the final foe falls. Enraged monsters have disadvantage on Deft and defense checks.
Monster phases allow you to build more engaging, unpredictable boss fights!
Homebrew Rules
You can see the exact calculus for making your own monsters in the Game Master's Guide.
Revised NPC Shorthand
You will find a fully revised NPC shorthand that incorporates these new rules.