Against an attacking Nia, Flabled Skyclimber, I blocked with the 2/2 Rebel with Hexgold Hoverwings attached. I used my Pippin, Guard of the Citadel to give my Rebel protection from creatures. This did not prevent the damage to the Rebel, although my opponent had no ability or spell that was cast that said damage cannot be prevented. I later blocked with Oaken Siren and gave it protection and it died as well.