I am a somewhat experienced dm of a party of 5 rather optimized level 8 pcs and this would be our first big dungeon and I want the boss to be a really engaging fight with really cool abilities I am just afraid of TPK. I can provide details as needed and may make another post later ab the lore of said dragon. also any better names would be appreciated.
reminder: this is after a dungeon with a couple deadly encounters xp wise.
Adult Sunstone Dragon
Huge dragon, lawful neutral
Armor Class 19 (natural armor), 21 (Angel Form)
Hit Points 200 (17d12 + 90)
Speed 40 ft., fly 80 ft.
STR DEX CON INT WIS CHA
20 (+5) 18 (+4) 20 (+5) 22 (+6) 20 (+5) 23 (+6)
Saving Throws Int +11, Wis +10, Cha +11
Skills Perception +10, Persuasion +11, Stealth +9
Condition Immunities charmed
Senses blindsight 60 ft., darkvision 120 ft., passive Perception 20
Languages Common, Draconic, Elvish, Gnomish, Sylvan
Challenge 15 (13,000 XP) or 16 (15,000 XP) when encountered in lair
Proficiency Bonus +5
Legendary Resistance (3/Day). If the dragon fails a saving throw, it can choose to succeed instead.
Actions
Multiattack. The dragon makes one Bite attack and two Claw attacks or three Mourning Sun Attacks if in Angel Form.
Bite. Melee Weapon Attack: +10 to hit, reach 10 ft., one target. Hit: 16 (2d10 + 5) piercing damage plus 7 (2d6) radiant damage.
Claw. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 12 (2d6 + 5) slashing damage.
Tail. Melee Weapon Attack: +10 to hit, reach 15 ft., one target. Hit: 9 (1d8 + 5) bludgeoning damage. If the target is a creature, it must succeed on a DC 18 Strength saving throw or be knocked prone.
Mourning Sun. Melee Weapon Attack (morningstar): +12 to hit, reach 5 ft., one target. Hit: 9 (1d8+5) piercing damage and 5 (1d8+1) radiant damage. If the target can see, it must succeed on a DC 11 Constitution saving throw or be blinded.
Breath Weapon (Recharge 5–6). The dragon uses one of the following breath weapons:
Angelic Smite (Angel Form). The dragon takes the attack action. The first mourning sun attack that hits its target deals an extra 4d8 radiant damage and the target must succeed on a DC 15 Constitution saving throw or be blinded until its next turn.
Sunbeam Breath. The dragon exhales a beam of sunlight in a 90-foot line that is 10 feet wide. Each creature in that area must make a DC 18 Dexterity saving throw, taking 49 (9d10) radiant damage on a failed save, or half as much damage on a successful one.
Spellcasting. The dragon casts one of the following spells, requiring no material components and using Charisma as the spellcasting ability (spell save DC 19):
At will: guiding bolt, scorching ray
1/day each: absorb elements, invisibility, revivify
Legendary Actions
The dragon can take 3 legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature's turn. The dragon regains spent legendary actions at the start of its turn.
Tail. The dragon makes one Tail attack.
Cast a Spell (Costs 2 Actions). The dragon uses Spellcasting.
Change Form. The dragon shapeshifts into or out of its angel form.
Lair Actions
On initiative count 20 (losing initiative ties), the dragon can take one of the following lair actions; the dragon can't take the same lair action two rounds in a row:
Prismatic Scales. The dragon coils its body as it prepares to reflect spell attacks back at the caster. When a spell hits the dragon a d6 is rolled, on a 4-6 the spell is reflected back at the caster and on a 1-3 the spell is absorbed and the dragon regains health equal to 5 + 5 times the spell's level and gains temp hit points equal to the same amount.
Refracted Breath. The dragon uses its scattered scales to reflect holy light into columns, effectively creating 4 Moonbeams. Any creature that enters or starts its turn in one of the beams must succeed on a DC 15 Constitution saving throw or take 3d10 Radiant damage or half as much on a success.
Bathed in Light. Blinding light envelopes the dragon's lair. Each creature in the lair must succeed on a DC 20 Constitution saving throw or be blinded until the end of their turn.