A good cover has a distinct silhouette
The silhouette says a lot with very little information, but that's also what the stereotype does.
Magnus stood up and went to the window. He pushed the curtain back, letting in just enough light to silhouette his hawklike profile. "Blood," he said, half to himself. "I had a dream two nights ago. I saw a city all of blood, with towers made of bone, and blood ran in the streets like water. " Simon slewed his eyes over to Jace. "Is standing by the window muttering about blood something he does all the time?" "No," said Jace, "sometimes he sits on the couch and does it.
Amid the moon and the stars, amid the clouds of the night, amid the hills which bordered on the sky with their magnificent silhouette of pointed cedars, amid the speckled patches of the moon, amid the temple buildings that emerged sparkling white out of the surrounding darkness - amid all this, I was intoxicated by the pellucid beauty of Uiko's treachery.