The legend says that there are 3 legendary creatures that appear every 8501 years. They are called the Sons of Oblivion. They are massively gigantic creatures, so big that when they hit nothing can be done to avoid them. They are classified as natural disasters.
Havoc is a massive planetoid, it is able to swallow an entire planet or star. Usually people can find a way to survive since, in order to eat, Havoc needs to pull is tongue out and that take from 6 months to 1 year. So usually people have time to go away on another planet. Things get worse only after the 2 months after the tongue is pulled out, because of gravity issues. --
Now, I took time to think about an epic story, draw the concept... then a friend just told me that this thing exist already in some comics... Damn!