Darkness
The Dark
noun
A dark darkness is a darkness. It's the dark.
The reading is the kun'yomi reading of both kanji. The reading from 暗い and the reading of the kanji 闇.
暗闇で戦う時は、相手の出方を見て、その上でどうするか判断した方がいいよ。
When you fight in dark you should let the other guy make the first move and then decide what to do.