Olrox17
Hero
Good point [MENTION=6801397]Olrox17[/MENTION], since you're surprised, you can't spend a reaction, which is required to boost your AC. Thanks for pointing that out and sorry for your 10 HP loss.
I just checked my PHB just to be sure. On surprise it says:
"If you’re surprised, you can’t move or take an action on your first turn of the combat, and you can’t take a reaction until that turn ends. A member of a group can be surprised even if the other members aren’t."
Maybe I can use a reaction, because my first turn has ended. The rule isn't very clear, though. It's open to interpretation.