Per Day

When a feature says it can be used "X times per day" or "once per day," the reset cycle is at dawn unless the feature specifies otherwise.

Standard reset:

• Uses replenish at dawn (typically the start of a new in-world day, after a long rest taken overnight)
• Whether the creature has rested is irrelevant; the dawn timer alone resets the uses
• If a creature has not used the ability since the previous dawn, the unused charges do not accumulate

Variant resets:

• "Per long rest" — resets on completion of a Long Rest; this is not the same as per-day. A character who long-rests twice in a 24-hour period (rare but possible) gets two resets of "per long rest" features but only one reset of "per day" features.
• "Per short rest" — resets on completion of a Short Rest; faster cadence
• "At sunset," "at midnight," "when the moon rises" — bespoke timers for specific abilities (often monster features tied to themes)
• "Per turn" or "per round" — combat-pacing limits that reset within the encounter

Why the distinction matters: "Per day" features tied to dawn are a softer leash than "per long rest" — a party that skips rest still gets the reset. "Per long rest" punishes pushing through. Many monster legendary abilities use "per day," allowing the DM to telegraph that the BBEG has fired its big shot for the day.

Magic items: Charged magic items almost always recharge "daily at dawn" with a number of charges. Items typically read "regains 1d6 + 4 expended charges daily at dawn" or similar.