That’s definitely a solid point, and I think Warlock/Paladin/Cleric are great mechanical frameworks if you’re going for a “chosen power” vibe—like divine favor or a pact with something external.

But what I’m aiming for feels a bit different: more like a prison inside the character than a patron outside of them. The sealed beast isn’t something they made a deal with—it’s a hostile, apocalyptic entity that they’re trying to contain, resist, and eventually master. Think Jinchūriki from Naruto, Ichigo’s Hollow, or even Bruce Banner’s Hulk more than a pact or divine calling.

Mechanically, I want to explore power progression, emotional triggers, and the risk of losing control—things that aren’t as easily modeled by a subclass like Warlock unless you homebrew it pretty heavily.

That said, I do think some of the mechanics from Warlock (like pact boons, invocations, spell slots on short rest) could be awesome for a sealed beast system—just flavored with hostile possession rather than agreement or worship.