Verses 3 to 6 offer important insight into the devil's tactics and motives. While first directing his comments to just Zeezrom, Alma makes clear that all the community around Zeezrom was also being taken advantage of through the devil's efforts.
What's more, these verses explain that the adversary actually had a plan for their destruction. His efforts were crafted to be subtle and imperceivable so that he may gain control of the community and the individual.
This is a reality that the adversary has power to exercise control over us. That is the only power that he has, but that is the whole thrust of his campaign of evil: so that he can bind us during this season of mortality to prevent us from experiencing the peace and happiness of a good life and ultimately, to obtain salvation.
At the end of verse 7, the writer makes this insightful observation: "for power was given unto them that they might know of these things according to the spirit of prophecy." This gift of the spirit of prophecy is required to be able to do the Lord's work. Later in Alma 17, it is observed that those missionaries that went among the Lamanites prayed and fasted much, and consequently they had the spirit of prophecy and the spirit of revelation.
On the topic of spirit of prophecy, I've taken a moment to review a talk given by Elder L. Aldin Porter of the Seventy entitled "The Spirit of Prophecy."
When, with heavenly power, [the witness of the Spirit] comes to a person, he or she will soon understand that personal sacrifice is its constant companion. The spiritual witness of these sacred things and the demands of sacrifice inevitably walk the road together. In time, one comes to understand the necessity of this and is filled with gratitude that it is so.
I thought to move on after having come this far in this study yesterday, but today I am reviewing notes made and passages read from both Alma 12 and the talk referenced above and have also read the First Presidency message on courage. All this together is helping me to understand both the priority of instruction received by revelation, the spirit of prophecy. In times passed, I had mistaken this power of the spirit of prophecy with keys of the priesthood. What I'm coming to realize though is that anyone, who is worthy, can be receptive to the spirit of prophecy.