What Lightning Storm Do?
When you cast Lightning Storm, every unit currently on the battlefield takes 2 damage.
The value of this is clearly situational. It can wipe out a cheap and cheerful army of low cost cards, however it doesn't make much of an impact against more powerful units. However even then it can be of value as a way of removing Aegis protection; if you're faced with half a dozen enemy units all protected by Aegis, Lightning Storm will mass remove the Aegis effects and open them up for other spell based attacks.
Note that this card will effect all units on the battlefield - yours as well as your opponent's. And Aegis does not protect your units from your spells. This isn't always a good thing as it can be a way of mass firing the Entomb skills of your cheap units. That can be especially useful if you're playing a Primal/Fire (Skycrag) deck and have cards such as Ticking Grenadin, Rebel Illuminator and Bait in play.
This page written for Eternal version 1.21, Card Set 1
Last updated: 9-07-2017