You have the choice to become biologically immortal. This means that you will never die of old age, but the usual things can still kill you—injury, disease, poison, etc.
However, once every 1-30 days, at a random time, you will be attacked by a nightmare monster known as "The Silent Man." The Silent Man is tall and lanky, but he walks on all fours. He moves quickly, and always knows exactly where you are. If he catches you, he will tear you apart with his insane strength.
The Silent Man hates noise, so he doesn't make any. No matter what he does—jump through a window, break down a wall, trigger an explosion—it will be completely and utterly silent.
The Silent Man cannot be physically harmed, but there are ways to repel him. Firstly, he can only be seen by one person at a time. If more than one person looks at him, he vanishes until the next attack.
Secondly, as previously stated, The Silent Man hates noise. Loud noises will repel him from a distance, but up close, they will only anger him and entice him to attack.
Lastly, despite his ability to vanish and defy physics, he is a physical being. He cannot phase through walls. However, he is extremely strong, and can break almost anything that would usually stand between him and his victims.
Very durable structures, like those made from steel, should be able to keep him out. Him attacking every 1-30 days means that after each attack, 1-30 days will pass before the next attack.
Now that you know what you're up against, would you accept the deal?