[MaxWilson]

Not necessarily. Darkness is great for almost anybody against, say, Helheim or Pangaea. Effectively it halves the difference between your units' attack and his units' defense. E.g. a regular spearman vs. a W9 Van:

Without darkness, (spearman) attack 10, (Van) defense 23, difference = -13 = 1% chance of hitting.

With darkness, (spearman) attack 5, (Van) defense 11, difference = -6 = 11% chance of hitting.

Of course the swarm factor will play into this too, but the point is that Darkness is a way of levelling the playing field, so it's useful against anyone who plays with elite units. Unless those elites have Darkvision, of course.

It also works great against arrows and spells, since it cuts precision by 75%.

-Max

Edit: hey, is R'lyeh freespawn upkeep-free? It might be really interesting to see R'lyeh casting Utterdark. Unexpected, anyway.