These are the chances of winning and the necessary attack power of hunting down certain monsters.
For example: To hunt for monster 7, your legion needs to have a minimum attack power of 20,000, and you have a 65% chance to win 74 USD.
Here is the reward table with its chances to win:
Special Monster 25
A 'Sunday Special' Monster 25 is available on Sundays only, with an exceptionally powerful reward, higher than any other monster. The requirement to be able to hunt for this Monster is that you have used a certain amount of summoned warriors to create new legions over the last 6 days since Monday 0:01am UTC. Updating existing legions does NOT count towards the requirement. You must use the required amount of warriors to create NEW legions. Only one legion will be able to attack this monster, and only once per week on Sundays. Monster 25 needs to be hunted individually, in other words the "mass hunt" option will not hunt for this monster.