If you’re thinking of making changes to a class, you’re probably concerned about doing something that makes the class too powerful – I believe the current term is “overtuned”? There’s a quick heuristic you can use in strongly class-based games like D&D.

First, pick a benchmark class – this is a class seen as one of the more powerful ones for the game, if not the most powerful. Let’s assume we’re looking at 5e, and the benchmark class is wizard.

Second, you ask these questions:

1. Is the class I’m modifying at least as powerful as the wizard before making these changes?

2. Will the change make the class I’m modifying more powerful than the wizard?

3. Am I doing anything to reduce the power of the wizard?

If the answer to all 3 of these is no, the change probably doesn’t make the class overpowered. We can’t be too certain – a change may not make a class too powerful on its own, but may do so in concert with various build choices like feats or multiclassing combinations. But this is a good first approximation.

Incidentally, this suggests that any improvement to your benchmark class is a bridge too far, at least if that class really is the most powerful class already. For 5e, that means don’t buff wizards. Well, I’m sure the designers of 5.5e already know that…