If you need to destroy just one more building to reach 50% destruction, a single Lightning Spell can be used to destroy a Builder's Hut, the Barbarian King or Archer Queen Altar, a Barracks (if its level is not higher than your Lightning Spell) or an Army Camp.

Can you kill Archer queen with lightning?

While the Barbarian King, Archer Queen, and Royal Champion altars can be destroyed with no problem, the Grand Warden Altar can only be readily destroyed if the defending Grand Warden is inactive.

Can Level 5 Lightning spell destroy air defense?

Lvl 1 earthquake spell actually does slightly more than 14% damage (maybe about 14.3%), although its info shows only 14%. Therefore, 1 lvl 1 earthquake and 2 lvl 5 lightning will do 1050 (or slightly more) damage, which is just enough to take down a lvl 6 air defense.