Card Rulings talk:Magic Cylinder

I used ultimate baseball kid, who has an original attak of 500, which at the time had 3500 attack, and I had magic cyilider used on me after I attepmted to attack a monster on my opponents side of the field. In my turn I attacked the monster then he activated his magic cylinder on me.

Do I loose:

-500 Life points or

- 3500 life points.