You must find a "pressure plate" nearby that glowing door to open it
You can't block attacks, but if you wish you can put points in the skill "Evade" or run and jump away to evade the attacks .
On 7th of february 2015 : I start a new adventure in the Divinity world of Original Sin, it's a Fantastic Freaking Fabulous Funny ... it's my All Time Favorite One !