Adult Gold Dragon

If the monster fails a saving throw, it can choose to succeed instead.

The monster can breathe air and water.

The monster makes three Rend attacks. It can replace one attack with a use of (A) Spellcasting to cast Guiding Bolt (level 2 version) or (B).

Melee Attack: +14 to hit. reach 10 ft. Hit: 2d8 + 8 slashing plus 1d8 fire damage.

Dexterity Save: DC 21. target: 15-foot-long, 5-foot-wide line, creature. Failure: 12d10 fire damage; success: half.

The monster casts one of the following spells, requiring no Material components and using Charisma as the spellcasting ability: At Will: Detect Magic, Guiding Bolt (level 2 version), Shapechange (Beast or Humanoid form only, no Temporary Hit Points gained from the spell, and no Concentration or Temporary Hit Points required to maintain the spell) 1/Day Each: Flame Strike, Zone of Truth

For the duration, you sense the presence of magical effects within 30 feet of yourself. If you sense such effects, you can take the Magic action to see a faint aura around any visible creature or object in the area that bears the magic, and if an effect was created by a spell, you learn the spell's school of magic. The spell is blocked by 1 foot of stone, dirt, or wood; 1 inch of metal; or a thin sheet of lead.

You hurl a bolt of light toward a creature within range. Make a ranged spell attack against the target. On a hit, it takes 4d6 Radiant damage, and the next attack roll made against it before the end of your next turn has Advantage. Using a Higher-Level Spell Slot. The damage increases by 1d6 for each spell slot level above 1.

You shape-shift into another creature for the duration or until you take a Magic action to shape-shift into a different eligible form. The new form must be of a creature that has a Challenge Rating no higher than your level or Challenge Rating. You must have seen the sort of creature before, and it can't be a Construct or an Undead. When you shape-shift, you gain a number of Temporary Hit Points equal to the Hit Points of the form. The spell ends early if you have no Temporary Hit Points left. Your game statistics are replaced by the stat block of the chosen form, but you retain your creature type; alignment; personality; Intelligence, Wisdom, and Charisma scores; Hit Points; Hit Point Dice; proficiencies; and ability to communicate. If you have the Spellcasting feature, you retain it too. Upon shape-shifting, you determine whether your equipment drops to the ground or changes in size and shape to fit the new form while you're in it.

A vertical column of brilliant fire roars down from above. Each creature in a 10-foot-radius, 40-foot-high Cylinder centered on a point within range makes a Dexterity saving throw, taking 5d6 Fire damage and 5d6 Radiant damage on a failed save or half as much damage on a successful one. Using a Higher-Level Spell Slot. The Fire damage and the Radiant damage increase by 1d6 for each spell slot level above 5.

You create a magical zone that guards against deception in a 15-foot-radius Sphere centered on a point within range. Until the spell ends, a creature that enters the spell's area for the first time on a turn or starts its turn there makes a Charisma saving throw. On a failed save, a creature can't speak a deliberate lie while in the radius. You know whether a creature succeeds or fails on this save. An affected creature is aware of the spell and can avoid answering questions to which it would normally respond with a lie. Such a creature can be evasive yet must be truthful.

Strength Save: DC 21. target: 60-foot cone, creature.

Charisma Save: DC 21. target: creature. Failure: 3d6 force damage.

The monster uses Spellcasting to cast Guiding Bolt (level 2 version).

You hurl a bolt of light toward a creature within range. Make a ranged spell attack against the target. On a hit, it takes 4d6 Radiant damage, and the next attack roll made against it before the end of your next turn has Advantage. Using a Higher-Level Spell Slot. The damage increases by 1d6 for each spell slot level above 1.

The monster moves up to half its Speed, and it makes one Rend attack.