It is not hard to burn through exertion and Herald has the huge benefit of choosing when then want more juice. Examples:
- Herald7/Fighter3;
- 29 exertion;
Should be 28: 8 from fighter (2x4pb) + 20 from herald (burning all 4 level 1 slots and all 3 level 2 slots)
- Two attacks;
- Brute Strength
- Activate Dispelling Assault (2), then add Brute Strength (2 x 4); Shrug it Off (2); Catch Your Breath (2) = 14
- Do this twice: 2 x 14 = 28
- Brute strength added damage (4 x 4d6) over two rounds.
Also should be 4x4d8, over 2 rounds
- Let's say you don't get a short rest and a battle ensues 10 minutes later. No problem. Burn 10HD for 10d4 (25 exertion). So you can sort of pull off the combo again. With a short rest you're definitely pulling it off again.
I don't think this would work. IMO you should only be able to recover the "normal" exertion pool from the fighter, as the one coming from slots is coming from slots, it's a separate pool. So you shouldn't be pulling this off again.
- Another combo to burn exertion would to combine Heighted Reflexes (3) and Intuitive Counterattack (2 x 4) and another maneuver (2) that uses your action - 6 attacks costing 13 exertion per round.
This is why I think the limits should be placed on how the slots can be used and how long they last ie., the Herald can use spell slots for exertion but they are super temporary - you get to use it on your turn and any excess is lost (I posted a list earlier in the thread).
Not sure capping their duration does anything to prevent these supernovae, if that's your goal, as converting spell slots into exertion doesn't cost an action, it's just something that can be done at the start of their turn.
One way to to mitigate this nova would be to make the conversion from spell slots to exertion more expensive. Another could be to cap the amount of exertion that can be spent per turn to some arbitrary threshold.
However do keep in mind one thing: spell slots are valuable for a herald (calculated retribution, force of will and crushing haymaker are all great spells IMO), and the usage of exertion for brute strenght not as needed sincce the herald could smite instead (4 day) for the same damage at no cost. In addition, there's empowered smites, which can be used 1/long rest and then is fuelled by spell slots. This is to say that while there is significant potential for nova when burning spell slots to fuel exertion, it also comes at a significant cost and it may not always be worth it.
Edit: Nevermind I think I found a RAW limitation that makes all this nova potential go away: under
combat maneuvers "
You have a maximum number of exertion points equal to double your proficiency bonus"