/estimate <i>ABILITY</i> [+- <i>D</i>] [, <i>OPTION</i>] — Estimate the result of rolling a 20-sided die, adding / subtracting the ability modifier and <i>D</i>, and comparing with <i>DC</i>.

<b>Skill Checks:</b>
/roll <i>SKILL</i> [, <i>OPTION</i>] — Roll a 20-sided die, add / subtract the skill and ability modifiers, and compare with <i>DC</i>.
/passive <i>SKILL</i> [, dc|difficulty <i>DC</i>] — Determine the passive score using the skill and ability modifiers, and compare with <i>DC</i>.
/estimate <i>SKILL</i> [, <i>OPTION</i>] — Estimate the result of rolling a 20-sided die, adding / subtracting the skill and ability modifiers, and comparing with <i>DC</i>.
/spellsave <i>SKILL</i> — Determine the spell save DC using the skill and ability modifiers of a magic skill.
/proficiency — Determine the proficiency bonus of the active character.

<b>Check Options:</b>
dc|difficulty <i>DC</i> — The <i>DC</i> of an ability or skill check may be specified as a number or it may be one of the adjectives <i>Very Easy</i>, <i>Easy</i>, <i>Medium</i>, <i>Hard</i>, <i>Very Hard</i>, or <i>Impossible</i>.
ins[piration] d<i>S</i> — An <i>S</i>-sided inspiration die may be added to a check. If multiple of these options are given, the highest <i>S</i> is used.
adv[antage]|dis[advantage]|normal — Checks may be performed at advantage, disadvantage or normal conditions. If multiple of these options are specified, the majority of advantage or disadvantage options determines the conditions.

<b>Character State:</b>

      | ["/spellsave"; Skill skill] ->
        let chr = selectedCharacter user
        let score = chr.GetSpellSave(skill)
        return Markup (
          sprintf "<i>%s</i> : DC = <b>%d</b>" (HttpUtility.HtmlEncode chr.Name) score,
          List.empty
        )
        
      | ["/proficiency"] ->
        let chr = selectedCharacter user
        return Markup (
          sprintf "<i>%s</i> : Proficiency Bonus = <b>%+d</b>" (HttpUtility.HtmlEncode chr.Name) chr.ProficiencyBonus,
          List.empty
        )
        
      | ["/show" | "/stat"] ->
        let chr = selectedCharacter user
        let buffer = Text.StringBuilder(1024)
        buffer
          .Append("<b>Name:</b> ").Append(HttpUtility.HtmlEncode chr.Name).Append('\n')
          .Append("<i>").Append(HttpUtility.HtmlEncode chr.Race)