What am I missing with Aberrant Mind & Clockwork Soul?

[HPisBS]

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Clockwork Soul grants you a trance ability that assuming you have a Cha of 20 by this point lets you auto hit anything with an AC 20, and automatically make any concentration check from taking 40 or less damage. While in this trance if you cast Counterspell or Dispel Magic even using a 3rd level slot you auto succeed against anything of 4th or 5th level too.

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I think you mean "you always auto succeed."

(DC is 10 + opposed spell's level, so max of 19.)



As for why all Sorcerers should or shouldn't get extra subclass spells, I'll just reiterate that without them, Sorcerers really do have it kinda rough with the fewest spells known of any full or even half caster, now that Tasha's added 5 more spells known for all Rangers.

Spoiler: For comparison

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A Shadow or Divine Soul Sorcerer now has the same number of spells known as a Beast Master or Hunter Ranger. Wild and Storm, one less. Compare to any other Ranger and the Sorcerer really starts looking like the redheaded stepchild of casters.

And with so few spells, you're liable to wind up building Sorcerers that barely have any spells tied to their Origin at all. Bonus spells would also provide an opportunity to give them spells that perfectly fit their theme, but that aren't on the Sorcerer's list. (Looking at you, Call Lightning and Storm Sorcerers!)