Reap is a strictly offensive spell, of after a bad push by an opponent picking off another unit, which still makes it offensive.I love reap, you can reap ninjas, and magez into medusa range. You can wreck giants. The spellcaster if fine. I use the two equally. Tho I wouldn't mind a hellfist buff even tho it is unlikely.
all the things that you mention can be done by Medusa and done better to be frank. One of the major reason marows are used is that their very good v archers but they cant hit archers very because archers move or some archer will take one fist while some might take 2. The damage doesn't feel equal in all area like blast. I appreciate that marrowkia can be useful to lure giants. you can reap cloacked ninjas but if you can reap a ninja in time you could probably have stoned it. Hell fists main use is anti archers and it doesn't furthil that role very well unless you can suggest another use for hell fists.
I was watching that TZ pod cast and they came up with two ideas
Marrowkia speed boost. I guess so you can get close enough to use hell fists quickly enough.
Cast speed incease I don't think this would work archers could still get out of the way.
Hellfists just needs a slight range increase and then we could take the problems with hell fists as a spell itself knowing that it has other benefits
A good order player times it right, you can't stone a ninja. reap is best way because as long as it is casted before ninja cloaks, it works. Medusa has a small range, so you reap things
into medusa or dead/eclipsor range to kill them. Hell fists wreck deads, air units, clumped spears, swords, ect. it si all a mater of how it is aimed and how the opponent reacts.
If you completely change hell fists to where it has an easier aim I personally think It'd have to be like this:
https://www.youtube.com/watch?v=WHktPFc4sqQ
Oni's ability where he stabs ground and the swords come up, except 1-3 fists come up and then a group come up in a circle where the circle was place (first 1-3 fists would be very similar to where they are now, and then a circle comes up doing high damage).
However a descent range increase would be very much a buff and fine by myself.