Yes, it is important to upgrade the lightning spell.
However, it is not a priority.
If you are more comfortable in aerial attacks using dragons and balloons then you can upgrade your lightning spell up to level 4 then you can focus on your other spells or troops to upgrade after that.
If you already have a level 4 lightning spell, three of them can already destroy a level 6 air defense so there is no need to prioritize them after that.
Enemy bases with air defenses higher that level 6 also means that they can already have 4 air defenses present in their camp, air attacks using lightning spells will not be very effective in these cases so upgrading them will not be a top priority anymore.
anoymous
