There are a few signs to indicate that the creature dark is ready to assault.
1. The emergence of the angry teeth. The creature will bare its front teeth when it gets mad.
2. The lengthening and hardening of the claws. This can happen in a flash so be alert!
Mike- "It's the creature dark! You have to keep it happy or else it'll go on a rampage. I couldn't get the sardine treats out in time and now it has already killed a few people. We have to find it!"
Reporter- "Sir, is that blood on your forehead?"
Mike- "Yes, it's those hard claws. I didn't notice the angry teeth until it was too late!"