Below are quick reference guide on completing some challenges using lightning spells along with level 4 earthquake spell (in some occasions).  You may use this guide to determine the number of lightning spell require for the respective level of each defense building type. 

Note: number of lightning spell may change in the future when SUPERCELL upate total damage per spell.

Whenever an earthquake spell are require, always drop it before lightning spell

 

Inferno Tower

  Lightning Lvl 5 Lightning Lvl 6 Lightning Lvl 7 TH
1 3 + 2 +  2 + 10
2 3 + 3 3 10
3 3 + 3 +   3 + 10
4   3 +   3 +  11
5   4 +   4 + 11
6    4 +  4 + 12

  + denotes 1 additional Level 4 Earthquake spell on top of the require lightning spell

 

X-Bow

  Lightning Lvl 5 Lightning Lvl 6 Lightning Lvl 7 TH
1 3 2 + 2 + 9
2 3 + 3 + 3 9
3   3 +  3 + 9
4   4 +  4 + 10
5   4 +  4 + 11
6    5 +  4 + 12

  + denotes 1 additional Level 4 Earthquake spell on top of the require lightning spell

 

Bomb Tower

  Lightning Lvl 5 Lightning Lvl 6 Lightning Lvl 7 TH
1 1 + 1 +  1 8
2 1 + 1 + 1 + 8
3 2 1 + 1 + 9
4 2 2 1 + 10
5 2 2 2 11
6 2 + 2 2 11
7 2 + 2 + 2 + 12

+ denotes 1 additional Level 4 Earthquake spell on top of the require lightning spell

 

Air Defense

  Lightning Lvl 5 Lightning Lvl 6 Lightning Lvl 7 TH
6 2 2 2 8
7 2 + 2 2 9
8 2 + 2 2 10
9 2 + 2 +  2 11
10 2 + 2 +  2 + 12

+ denotes 1 additional Level 4 Earthquake spell on top of the require lightning spell

Clan Castle

  Lightning Lvl 6 Lightning Lvl 7 TH
4 4 + 4 8
5 4 + 4 + 9
6 3 +  4 + 10
7 5 +  5 + 11
8 6 +  5 + 12

+ denotes 1 additional Level 4 Earthquake spell on top of the require lightning spell

 

Eagle Artillery

  Lightning Lvl 6 Lightning Lvl 7 TH
1 5 + 5 + 11
2 6 + 5 + 11
3 6 + 6 + 12

+ denotes 1 additional Level 4 Earthquake spell on top of the require lightning spell

   

Air Sweeper

  Lightning Lvl 5 Lightning Lvl 6 Lightning Lvl 7 TH
1 2 1 + 1 + 6
2 2 1 + 1 + 6
3 2 2 1 + 7
4 2 2 2 8
5 2 2 2 9
6 2 2 2 10
7 2 2 2 11

+ denotes 1 additional Level 4 Earthquake spell on top of the require lightning spell

 

Mortar

  Lightning Lvl 5 Lightning Lvl 6 Lightning Lvl 7 TH
4 1 + 1 1 6
5 1 + 1 1 7
6 1 + 2 1 + 8
7 1 + 2 1 + 9
8 2 2 1 + 10
9 2 2 1 + 11
10 2 2 1 + 11
11 2 2 2 12

+ denotes 1 additional Level 4 Earthquake spell on top of the require lightning spell