I wanted to do in my own roguelike THE EYE but i dropped workin on this years ago, so damn years of work needed, not on my human strength to carry - but this idea is really refreshing i think and could be incorporated with adom with great advantage
the thing:
Add a new value close to HP and PP with close range of values that
would denote some kind of stamina/energy/vitality of given char
(i propose tu use SP stamina points)
You could then use this power points to booost temporarily speed of given character for example by +5 speed on one usage (on given jkeypress like 'o' - you could accumulate this (like make 3 activating keypresses) to raise the boost more (for example to +14 value)
then teh boost will be decreasing and consuming SP - if SP is zero or maybe even below zero you could not activate the boost and maybe you will recive come slowdown penalty)
possibly you could also boost a little to hit to damage maybe also DV a bit not ony a aspeed (though speed semm most important)
How large the boost will be should depend on race-profesion combination, also how many SP points given character have (barbarians should give it much more then others i think)
It would be very fine to boost characer for good fight, and also take
a danger of situation when it drops down, It also helps to give new character characteristics (whole separate new dimension to it)
as boost may wary (in strength, maybe even a little in effect)
It also could give more meaning to such stat as willpower as
for example SP may depend on willpower, make it yet more
noticable for fighters, After all it could make fights more tactical
and cleaver
In general i am quite sure that this is especialy good idea making
the basic thing in adom it is fights deeper and more satisfactionary in some reletively easy way
*if TB reads, may use it freely, ofc, could be fun)