I did extensive raiding with level 2 drags when I was a th7 to raise DE. I found that 2 xbows pointed up were worth 3 ADs.... I once attacked a th 9 with two ADs under construction and I zapped a third. The single AD plus xbows pointed up and lvl 10 archer towers were enough to stop me from even 1 starring. Your mileage may vary because dragons are dumb and weird.
