A blistering short post.
The rules as written calculate the saving throw DCs of spells using the following formula:
10 + Spell Level + Ability Score Modifier
The ability score modifier used is the same ability score that governs the magic-user’s spellcasting powers: so Intelligence for a wizard, Wisdom for a cleric, Charisma for a bard and so on.
The current house rules calculate spell DCs using a different formula:
10 + ½ Caster Level (rounded down) + Ability Score Modifier
Which version shall we use?
The Three Tests
No problems here. It’s just how we set the DC. It doesn’t make any difference to the story of the campaign world.
Games without Miniatures
Again no issues. This is just as easy to adjudicate with or without little plastic figures.
So it boils down to this. The house rules equalise the DCs between spells and supernatural abilities. Any monster or class that has a supernatural or spell-like ability uses the hosue rule formula already. So this is already something that exists and works in game, and is already balanced against the saving throws of character classes. I don’t think we have anything to worry about on the imbalance front.
What these rules do is big up lower level spells, and make them more valid choices at higher levels. The rule is stating that the power of the spell comes from the caster and not the spell itself. A charm person cast by a twentieth level wizard should be harder to resist than the same spell cast by a first level wizard.
However, you may argue that the game already takes that into account, because your twentieth level wizard will have a higher ability score modifier than your first level wizard. You may also think that there should be a graduated difficulty in spell DCs, rather than having one DC fit all spells.
Our Pact of Minimal Tinkering states that we use the rules as written and ignore these house rules. However, I like these house rules. I don’t like them enough to make a big issue of it if you want to drop them: but I would like to have the discussion.