Hierophant Medusa

{
  "name": "Hierophant Medusa",
  "__prop": "legendaryGroup",
  "source": "BMT",
  "lairActions": [
    "On initiative count 20 (losing initiative ties), the medusa can take one of the following lair actions; the medusa can't take the same lair action two rounds in a row:",
    {
      "type": "list",
      "items": [
        {
          "name": "Petrifying Wave",
          "type": "item",
          "entry": "Up to three creatures the medusa can see within the lair are partially turned to stone. Each target must make a {@dc 15} Constitution saving throw. On a failed save, a target's speed is reduced to 0 and can't increase. On a successful save, its speed is halved. The target's speed returns to normal on initiative count 20 on the following round."
        },
        {
          "name": "Sudden Stonework",
          "type": "item",
          "entry": "The medusa creates a wall of stone on a solid surface it can see within the lair. The wall can be up to 60 feet long, 20 feet high, and 1 foot thick. Each 5-foot section of the wall has an AC of 17; 30 hit points; vulnerability to thunder damage; and immunity to poison, psychic, and slashing damage. A creature in the wall's space when the wall appears is pushed to the nearest unoccupied space on one side of the wall and must make a {@dc 15} Dexterity saving throw. On a failed save, the medusa chooses the side. On a successful save, the creature chooses the side. The wall disappears when the medusa uses this lair action again or when the medusa dies."
        },
        {
          "name": "Undulating Surface",
          "type": "item",
          "entry": "Solid surfaces within the lair ripple like a snake's coils. Up to three creatures the medusa can see within the lair can move up to 30 feet along solid surfaces without provoking opportunity attacks. If a creature moves along a surface such as a ceiling with no way to remain there (for example, sufficient handholds), it falls at the end of this movement."
        }
      ],
      "style": "list-hang-notitle"
    }
  ],
  "regionalEffects": [
    "The region containing a medusa's lair is altered by the medusa's presence, creating one or more of the following effects:",
    {
      "type": "list",
      "items": [
        {
          "name": "Faces in Stone",
          "type": "item",
          "entry": "Stone within 3 miles of the lair takes on subtle shapes that suggest people, animals, and other creatures when viewed from the corner of the eye or through dim light or fog."
        },
        {
          "name": "Gathered Knowledge",
          "type": "item",
          "entry": "Within the lair, creatures have advantage on ability checks made to discover or recall information relevant to the medusa's divine purpose."
        }
      ],
      "style": "list-hang-notitle"
    },
    "If the medusa dies, these effects fade over the course of {@dice 1d10} days."
  ]
}