The FAQ is online see:
FAQ online
Finally!
I'm reading through it now, but this ruling seems very odd to me:
Q: Is a player required to wound a unit in order to play
“Summon Lightning?” Can he play the card if the
opponent has no units to be destroyed?
A: A player may play “Summon Lightning” even if he
doesn’t have a unit to wound, and he may play it even
if the opponent does not have a unit to be destroyed.
I always saw Summon Lightning as a cost that needed to be paid to do an effect. This card is so much better now! Let's say you are defending a siege. Your opponent plays a unit. You play a cheap unit. Your opponent destroys your unit. You play Summon Lightning to clear his units. Well … considering it takes up one card slot in your hand, it may not be all that great compared to an extra unit, but I'll have to play with this rule to see how it goes. It's certainly exciting.
Also have to add how insane it is that you can spend gold without purchasing things. It's great for everyone since you can move gold out of your hand before ending your turn if you don't want to clog up your deck, and it's excellent for the Orcs. It's one rule that I ruled exactly opposite in my games. This will change things up.