I just did a quick test of Reveal Hidden in Blood Bay (on the Isle of Bones, there are several waves of Shock Monkey Gamma, that start off hidden/stealthed). Anyhow, reveal hidden did not seem to reveal them (the hidden monkey's were definitely within the spell's cast area). I guess its possible that my Reveal Hidden Skill level (55) was not enough to be successful, but the tool tip says 115% effective. Also, the tool tip states that the skill only works against hostile targets. Technically, the Shock Monkeys are not hostile while they are hidden (they have not agro-ed to me, and they are just sitting there). So, maybe that is the problem. Anyhow, I never bothered training this skill up much because i found it useless. Perhaps it could be used to identify a PVP player that is stealthed, but the skill is an instantaneous reveal only (it does not continue to be effective for some time, like night vision). By the time you cast the spell, any PVPer is probably already attacking you. Incidentally, I tried reveal hidden in a duel. The other player stealthed, and I cast reveal hidden directly on top of him. Perhaps it revealed his presence 1 out of 10 casts (or perhaps it didn't, it was sometimes hard to tell if my proximity or something else caused the reveal). Again, maybe my skill level was not high enough to make reveal sufficiently effective. But my tests certainly did not alter my perception of this skill being useless.
It is practically useless. In part because it is a spell that you cast at a place and works instantly - how would you know if there would be invisible enemies at that place? Or would you spam Reveal Hidden left and right the entire time? It would make more sense if it would work like Nightvision where the spell lingers and enhances the avatars vision, but with Reveal Hidden to see invisible enemies for a while. But it is also useless because Nightvision has taken over an important part that should be limited to Reveal Hidden: Invisible Walkways, Invisible Walls that players use, or the invisible walls in the dungeons maze are hidden and revealed by - Nightvision. Nightvision is a "remaining light enhancer" that allows to see in darkness, but it is not described as revealing invisible stuff, so it should not while Reveal Hidden ought to.
