Cast Camouflage only during your declare attackers step.
This turn, instead of declaring blockers, each defending player chooses any number of creatures he or she controls and divides them into a number of piles equal to the number of attacking creatures for whom that player is the defending player. Assign each pile to a different one of those attacking creatures at random. Each creature that can block the creature its pile is assigned to does so. (Piles can be empty.)