Do you keep Ability Score Increases from Manuals when Shapechanged?

Question

Shapechange is a 9th level spell that lets you assume the form of a different creature, replacing your game statistics, including your Strength, Dexterity and Constitution scores, by that of your new form (but keeping your initial Intelligence, Wisdom and Charisma scores, as well as any benefits from your race, class and other sources).

The Manuals of Gainful Exercice, Quickness of Action and Bodily Health are very rare magic items that can be used to respectively increase your Strength, Dexterity and Constitution scores.

What's ambiguous for me is the above other sources, when pertaining to persistent effects from magic items such as the Manuals. For instance, if a Human Druid, who has pre-emptively read a Manual of Gainful Exercice, casts Shapechange to turn into a Frost Giant Everlasting One (Strength score of 25), is their Strength score 25, or 27 because of the book's persistent magic ? Do you keep Ability Score Increases from Manuals when Shapechanged ?

Answer 1

The Manuals increase the abilities of your natural form only.

The reason for this is twofold:

1. The Shapechanged form replaces your Strength, Dexterity, and Constitution.

In fact, it replaces everything except the qualities that are specifically exempted (such as your alignment, skill proficiencies, and class features). You become a frost giant, your Strength is now 25 instead of whatever it was before.

You've misquoted Shapechange slightly: what it says is "You retain the benefit of any features from your class, race, or other source...". What a Manual gives you is an ability score change, not a feature. Features are the kind of stuff that's listed under "class features" in your class description, like Spellcasting or Extra Attacks or Channel Divinity.

2. It's impractical to keep track of how you got those ability scores.

When you study a Manual and gain a permanent +2 Strength, do you write "+2 (Manual of Gainful Exercise)" next to your Strength score on your sheet? No, because it doesn't matter. You erase the number and write a new one, right?

It's unreasonable to expect that players will be able to backtrack through everything that's adjusted their ability scores and separate it out to figure out what applies to their Shapechanged form and what doesn't. 5e abolished "typed bonuses" for a reason; don't try to bring them back.