A very powerful symmetrical event that is great to punish an opponent summoner that does not want to participate. If that is the case, Valeria can jump in the fray of battle with a high level of impunity, decimating enemy commons and your opponent won’t be able to take advantage of this event.
Even if the opponent summoner is in the fray of battle you may want to use this event to be able to get Valeria in and kill enemy commons, but beware as some summoners are just as or even more scary than Valeria when they are protected!
If you need Valeria to jump in to clear out enemy commons, often this event will give her the protection she needs to not worry about the counterattacks.