Nobody messed with the Werewolves during the full moon, it was a well-known fact that was heeded by many. Be it the powerful Demons with their immortal army—the Undead with their power of the dead, the Vampires, the Shapeshifters—everyone respected the full moon.
It doesn't matter how strong but the Werewolves are invincible during the full moon.
Anyone who dared to clash against them would suffer immense casualties.
Simply put, the power of the full moon made the Werewolves unpredictable and horrifying.
Across all types of full moons, each one of them made Werewolves stronger and very hard to kill. Killing Werewolves are already hard enough, the strong ones even have regeneration that goes through the influence of silver.
Coupled with the full moon, the turnover was simply too much for everyone to handle.
Killing a single Werewolf would probably need three to five of the same realm.
But the mutated animals didn't know that.