I'm confused by the wording of the Way of the Four Elements monk's Fangs of the Fire Snake elemental discipline.
Specifically, how long does its bonus to the reach of unarmed strikes last, and how many times is the extra fire damage applied?
Here is an example scenario, with how I think it works:
A level 8 monk gets 2 attacks on his turn during the attack action, and a bonus action for Flurry of Blows, giving 2 additional unarmed strikes and a total of 4 unarmed strikes on his turn for 1 ki.
If he spends 1 ki for Fangs of the Fire Snake, the unarmed damage changes from bludgeoning to fire damage, and the reach is increased to a total of 15 ft.
When the monk's turn ends, Fangs of the Fire Snake ends, so it is not possible to make an opportunity attack with this discipline.
If I hit with an attack I can expend another ki to add 1d10 of fire damage. This extra damage only applies to that singular hit, the next attacks don't have the extra fire damage, and I can't expend more ki to add another 1d10 on those attacks.
Is my interpretation of how the discipline works correct?