Ordered outcome labels

At the table

Some games speak in named bands (failure, success, critical) instead of a raw total. You still want exact probabilities—and sometimes “success or better” on that ladder.

Try it

In the playground, open this lesson in the playground and click Run (or press Shift+Enter).

The script

↗Scale = (
    scale()
    .step("CRITICAL_FAIL", ..5)
    .step("FAIL", 6..10)
    .step("SUCCESS", 11..15)
    .step("CRITICAL_SUCCESS", 16..)
)
roll = 1d20
out = roll.bucket(Scale)
output("check", out)
output("p_success_plus", out.p_at_least("SUCCESS"))

• scale() starts an empty ladder; each .step(label, band) adds one rank (low → high). Omit the band when you only need labels for classify.
• Bands may overlap; use early=True on narrow steps so they match before broader bands without reordering the ladder (see lesson 12).
• Bands on Scale map each total into a label (..5, 6..10, 11..15, 16..). roll.bucket(Scale) uses them (same odds as bucket(roll, scale, [5, 10, 15]) with a label-only scale).
• output on a Outcomes shows a probability table (each label and its exact chance) in scale order in text and json.
• p_at_least("SUCCESS") sums every label at that rank or higher.

Reading the result

The text tab lists each label and its probability. The json tab uses "kind": "ordinal" with scale and entries.

Try this

• Change the ranges to match your game’s DC bands.
• Add out.p_at_most("FAIL") for “failure or worse.”

Builtin details: standard library reference (scale, Scale.step, bucket).

What’s next

D&D 5e d20 checks—nat 1, nat 20, advantage, and modifiers with scale().step(...) on the natural die (not fixed bands on 1d20 alone, and not 1d20 + MOD for true 5e crits).

For two dice with custom rules (e.g. white/black PbtA-style), see games-systems/white-and-black-story.dice and joint_classify in the reference.

check · Outcomes

p_success_plus · Prob