If a paladin has a negative Charisma modifier, how many times can they use the Divine Sense feature (per long rest)?

Question

The description of the paladin's Divine Sense feature says, in part:

You can use this feature a number of times equal to 1 + your Charisma modifier. When you finish a long rest, you regain all expended uses.

Unlike many abilities in 5e, it doesn't specify "a minimum of 1". This brought up an interesting question at my table:

What happen if the paladin has a negative Charisma modifier?

With an 8, you could do the calculation 1 - 1 and get 0 uses, which could make sense, but in our group the paladin rolled a 6 for their Charisma score, so 1 - 2 = -1 uses.

(Please don't comment on our paladin having Charisma as his dump stat; his choice, not mine.)

Answer 1

Technically, negative modifiers apply unless otherwise stated.

You’ve made the right observations: when a negative modifier does not apply, feature descriptions take care to set minimums to avoid things like this. As written, the paladin would have zero available uses of Divine Sense.

Ask the Paladin what they want to do here.

A paladin with 8 charisma is likely not an accident. Choices were made. Ask the paladin how they want to rule on this. Does having zero uses of this feature fit into the character concept they are going for? You’re obviously not going to unbalance things by letting them have one use when they would otherwise have zero (since most paladins have several). So just let the paladin choose which ruling would be the most fun for them.

Answer 2

The paladin cannot use Divine Sense.

As you state, this feature lacks an explicit minimum: your 6-Charisma paladin can use his Divine Sense feature −1 times per long rest—or rather, not at all, because he does not have any uses. In short: exactly as many times as the feature states.

Answer 3

A negative number of uses is not covered by the rules

I think you are not asking if the Paladin should have 0 or 1 uses. I think you are asking what it means to have -1 (negative one) uses.

The rules do not foresee or cover this case. The most natural ruling would appear to treat this as having 0 uses, as there are no good alternatives: -1 is worse than 0, so it would make no sense to allow 1 use. And you cannot play having -1 uses, there is nothing positive to offset them against and no way you could use something less than not at all.