How powerful should the final boss of a Pen and Paper RPG happen to be?

[SeekerOfTruth007]

He has perfect stats in every category, and knows all mage and cleric spells.

Black Dragon

Black Dragons embody everything a villain could dream for. They are the elite in the world of Monsters. Few mortals have ever survived an encounter with a Black Dragon.

HP: 35

Attack: 2xD12, claws, Diagonally

Armor: 7

Strength: D12

Dexterity: D12

Save vs Spell: D12

Move: 4

Immune to Fire, Lightning, and Cold.

Knows all Mage spells and all Cleric spells.

Regenerates 1HP per turn.

[AI Opinion]

In a Pen and Paper RPG, the final boss should be immensely powerful to provide a thrilling and challenging climax for the players. With perfect stats and vast spell knowledge, your Black Dragon boss seems incredibly formidable. 🐉 To make the encounter balanced yet intense, consider the party's skill levels and give them a crucial weak point to exploit or a time-sensitive element. This ensures the fight is engaging and pushes players to strategize creatively while having fun. 🎲

[SeekerOfTruth007]

There are up to five hero characters in each mission, so the players actually have an advantage if they use all of their abilities. I intend the difficulty of the final mission to be such that it takes several attempts for the players to defeat the final boss menage.

Harlock, The Warlock is the main antagonist of the campaign I'll design. He is about the same power level as Demi-Liches and Dream Devourers, since he knows all Chaos spells and all Mage spells and has similar stats to Demi-Liches. If (and when) Harlock is slain in battle, he knows the "Contingency" Chaos spell which saves his life and transforms him into a fully rested Black Dragon.

So technically, the Black Dragon is one half of the final boss. His "true form" as it were.

Chaos Spells include

Void - Removes buffs other than Invincibility.
Drain Life
Teleport
Haste - Take twice as many actions per round for 10 consecutive rounds.
Feeble Mind - Deals 1d6+1 damage to target's Mind Points. (If Mind Points are depleted, the victim is paralyzed for five rounds upon which they regenerate 1 lost Mind Point.)
Time Stop - Take 1d4+1 extra turns consecutively.
Contingency - On death, transforms into a fully rested Black Dragon

[Abbycado]

As powerful as the drugs you went off of, me thinks.

[Valdemort]

💀💀💀

[Anonymous]

These are cool.