If you have a level in Fighter, you get
2x proficiency bonus exertion points per short rest.
Comparing vs. a level 8 Herald, a level 9 Herald does have two extra 3rd level spell slots, the equivalent of 2x 2x 3 =
12 exertion points per long rest. Given 2 short rests per long rest, that's the
equivalent of 4 extra exertion points per short rest.
Now comparing Herald 8/Fighter 1 vs. Herald 9 for exertion points per short rest, the former has 8 vs. 2 for the latter. So, the single-level Fighter dip provides more exertion points for combat maneuvers.
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In my opinion, this indicates a problem in the multi-classing or Herald mechanics. Maybe Herald should have been implemented instead with using exertion points to cast spells, with 2x proficiency bonus exertion points, instead of getting spell slots.
A level 9 Herald has 4x 1st + 3x 2nd + 2x 3rd spell slots, equivalent of 16 exertion points per long rest, or ~5 per short rest by the A5E rules as written. I would implement it something like this:
- They get 2x proficiency bonus exertion per short rest, like Fighter and other classes, instead of getting spell slots.
- 2 exertion points to cast a level 1 spell. Available from Herald level 1, as normal.
- 3 exertion points to cast a level 2 spell. Available from Herald level 5, as normal.
- 5 exertion points to cast a level 3 spell. Available from Herald level 9, as normal.
At level 9 with 8 exertion points, they can cast 1x 3rd level spell and 1x 2nd level spell after each short rest; or 2x 2nd level + 1x 1st level; or 4x 1st level. This is about right, maybe slightly low vs. the standard Herald class. Also, hit dice can be expended to recover 1d4 exertion (per LUA5E page 457), which I would allow for activating combat maneuvers, but I think this would be too good if allowed for spell casting.