3.5: breathweapon rounds explanation, please?

[Harlot]

I'm building a half-dragon - 'Races of the dragon' states:



DRAGON BREATH (FEAT)
You can use your breath weapon as often as a normal dragon.
Prerequisites: Half-dragon, 6 HD, breath weapon.
Benefit: You can use your breath weapon every 1d4
rounds.
Normal: A half-dragon’s breath weapon can only be
used once per day.

If I take this feat, how do I roll the 1d4?

Do I roll this 'once and for all' when I roll up my character (so if I should roll a 1 I could use this weapon every round, always) or do I roll a 1d4 before my turn in every encounter and the that roll would count for that encounter only?

Thanks for helping
/Harlot

[Fax Celestis]

Once you use the breath weapon, roll 1d4. That value is the number of turns that must pass before you can use it again. At the start of your turn, decrement that value by 1: once it hits 0, you can use your breath weapon again. This is per-instance of using your breath weapon. If you use your breath weapon three times in one combat, you roll each time.

Generally, I track it by just rolling a d4 and then rotating the die to the updated value when I start my turn.

[Harlot]

That was easy - thank you!