/open5e <i>QUERY</i> — Import a new character from Open5e and select it for the user who is asking.
/setname <i>NAME</i> — Change the name of the active character.
/setrace <i>RACE</i> — Change the race of the active character. This operation does not work on imported characters.
/set ac =|+=|-= <i>N</i> — Change the armor class of the active character.
/set hp =|+=|-= <i>N</i> — Change the maximum hit points of the active character.
/set <i>SPEED</i> =|+=|-= <i>N</i> — Change a movement speed of the active character.
/set <i>ABILITY</i> =|+=|-= <i>N</i> — Change an ability score of the active character.
/addlevel <i>CLASS</i> [, <i>N</i>] — Add one or more levels in the given class to the active character. This operation does not work on imported characters.
/removelevel <i>CLASS</i> [, <i>N</i>] — Remove one or more levels in the given class to the active character. This operation does not work on imported characters.
/addproficiency <i>SKILL</i> [, <i>N</i>] — Add a proficiency in the given skill, optionally with a multiplier, to the active character. This operation does not work on imported characters.
/removeproficiency <i>SKILL</i> — Remove the proficiency in the given skill from the active character. This operation does not work on imported characters.
/set <i>SKILL</i> =|+=|-= <i>N</i> — Change a skill proficiency modifier of the active character.
/adddefense <i>DAMAGE</i>, <i>DEFENSE</i> — Add a defense against <i>DAMAGE</i> for the active character. <i>DEFENSE</i> may be a numerical factor or one of the adjectives <i>Normal</i>, <i>Immune</i>, <i>Invulnerable</i>, <i>Resistant</i>, <i>Vulnerable</i>.
/removedefense <i>DAMAGE</i> — Remove the defense against <i>DAMAGE</i> for the active character.
/set <i>SENSE</i> =|+=|-= <i>N</i> — Change a perception sense range of the active character.
/addlanguage <i>NAME</i> — Add a language proficiency to the active character.

        let buffer = Text.StringBuilder("<i>").Append(HttpUtility.HtmlEncode chr.Name).Append("</i> : ")
        let pos = buffer.Append("Defenses = ").Length
        for damage, f in chr.Defenses do
          if buffer.Length > pos then buffer.Append(", ") |> ignore
          buffer.Append(Defense.toString f).Append(" against ").Append(Damage.toString damage) |> ignore
        if buffer.Length = pos then buffer.Append("None") |> ignore
        return Markup (buffer.ToString(), List.empty)
        
      | ["/addlevel" | "/removelevel"] ->
        return Markup (
          "<b>Note:</b> Select a character class",
          Profession.All
          |> Seq.chunkBySize 2
          |> Seq.map (
            Seq.map (fun prof ->
              let s = Profession.toString prof
              (s, s)
            )
            >> Seq.toList
          )
          |> Seq.toList
        )
        
      | ["/addlevel"; prof] ->
        let chr = selectedCharacter user
        let prof = Profession.ofString prof
        chr.AddLevel(prof)
        return Markup (
          sprintf "<i>%s</i> : Profession = %s" (HttpUtility.HtmlEncode chr.Name) chr.Profession,
          List.empty
        )
        
      | ["/addlevel"; prof; count] ->
        let chr = selectedCharacter user
        let prof = Profession.ofString prof
        let count = int count
        chr.AddLevel(prof, count)
        return Markup (
          sprintf "<i>%s</i> : Profession = %s" (HttpUtility.HtmlEncode chr.Name) chr.Profession,
          List.empty
        )
        
      | ["/removelevel"; prof] ->
        let chr = selectedCharacter user
        let prof = Profession.ofString prof
        chr.RemoveLevel(prof)
        return Markup (
          sprintf "<i>%s</i> : Profession = %s" (HttpUtility.HtmlEncode chr.Name) chr.Profession,
          List.empty
        )
        
      | ["/removelevel"; prof; count] ->
        let chr = selectedCharacter user
        let prof = Profession.ofString prof
        let count = int count
        chr.RemoveLevel(prof, count)
        return Markup (
          sprintf "<i>%s</i> : Profession = %s" (HttpUtility.HtmlEncode chr.Name) chr.Profession,
          List.empty
        )
      
      | ["/addproficiency" | "/removeproficiency"] ->
        return Markup (
          "<b>Note:</b> Select a skill proficiency",
          Skill.All
          |> Set.remove Skill.StrengthAttack
          |> Set.remove Skill.DexterityAttack

        let dup s = s, s
        return Markup (
          "<b>Note:</b> Select a language proficiency",
          [
            yield!
              Language.Standard
              |> Seq.chunkBySize 4
              |> Seq.map (Seq.map dup >> Seq.toList)
            yield!
              Language.Exotic
              |> Seq.chunkBySize 4
              |> Seq.map (Seq.map dup >> Seq.toList)
            yield
              Language.Secret
              |> Seq.map dup
              |> Seq.toList
          ]
        )