I'm stuck with those two virtues&abilities I have never used, and since both could eventualy be used to find vis sources (as a natural resource of the world), i'm starting to wonder which would be best... and wondering this, i'm starting to ask myself: what have they in common and what are the differences?
And sincerelly, from reading the ability description it is not very clear.
So if you have any insight on the matter, on how they are similar and how they are different, and which, in your opinion, is best suited to find the vis sources lying in the world and expecting to be found and harvested, please, share with me!
Have a good day.
Dowsing - I'm pretty sure in HMRE under the section on Hedge Witches, it says this tradition uses dowsing to locate vis. So presumably you take a pawn of existing vis and try to dowse for more - whether it will find any old vis, vis that matches the form or only vis that is similarly shaped (magic plant, magic animal, strange pebble, etc.) presumably depends on your saga.
ArM p64 states "Increased distances or dowsing for less common things increases the target number" so trying to find vis at a distance may be quite difficult.
Wilderness sense - ArM p67 states "A Perception + Wilderness Sense roll against an Ease Factor of 9 lets you determine the direction of north, the upcoming weather, or the presence of natural hazards or resources." Therefore it depends on whether your troupe considers vis occurring in the area a natural resource (because it spontaneously appears in the area) or an unnatural resource, as vis is inherently magical and may defy normal natural properties. If it does work, the fact that the difficulty is 9 regardless of range or substance probably makes it superior. Actually, this probably makes dowsing worthless unless Wilderness Sense has a restriction eg "natural resource" means animal, vegetable or water rather than the presence of mineral ores, or that Wilderness Sense only works on things exposed to the open air but dowsing allows you to locate underground resources (as traditionally dowsing is used to find underground water supplies or lost/buried items).
As written Dowsing always seemed more of a 'find your lost cufflinks' sort of thing than a 'find natural resources' sort of thing. Given the EFs for even moderate distances, you're really going to be limited to small areas. Say you were looking for water(a classic example of Dowsing). You'd be restricted to looking in a very small area if you wanted to have any chance of success. And the odds that the water actually being in that area are minimal. Ditto for vis searches, which probably require a much greater area to search in.
Then again, you can dowse over and over again, if you're willing to take two minutes for each pop. So if you set up a grid-pattern search, you could cover a fairly large area in an hour or two of searching, while keeping the EF for each search to a reasonable number.
I guess what really is useless is a folk witch's potion of Dowsing. That only works for one search, so you can't repeat it without taking another potion. So it's only good when you know what you're searching for is in a fairly small area. And then a simple physical search might well do the trick.
Though I suppose if you're on a vis hunt and get close but can't find the actual vis, a Dowsing potion might help you take that last step to find the vis. So, I guess it has some use. But again, a manual search might do just as well in that circumstance.
In term of efficiency to locate virtus, I always ruled and played: Dowsing > Magical Sensitivity > Wilderness Sense.
Keep in mind that it reflects more a personal understanding than purely RAW:
Dowsing is designed to find stuff that you are looking for. I won't help you find your way out of the bush, but if you are looking for ore, water or vis, it is designed for that. It can possibly help you locate somebody. In most case, you need a sample of what you are looking for, or an arcane connection if you are trying to locate somebody.
Magical Sensitivity: it will makes easy spotting magical things. It won't guide you to them, but if you are within sight range of one, it should glow/smell/tickle.
Wilderness Sense: it acts like a danger sense, an uncanny sense of direction, and a weather forecast station. It also acts like super Survival skill when it comes to foraging and finding natural resources, which I don't consider vis to be one.
So, by itself, Dowsing is the most efficient one. However, if you have Wilderness Sense and you have another skills which will help you identify virtus (herbalism, magic theory, magical sensitivity, philosophae...), then combining both could be as efficient, while with reduced risks. Wilderness will help you find your way, locate a place untouched by human where the likelyhood of finding virtus is higher. It probably won't lead you to the physical remain of a demonic body, destroyed undead or the corpse of magical animal though.
Thanks all, particularly Ezechiel. Your reflexion inspired me and I agree with what you write.