So far FG-level opponents have been described as rare elite mobs/boss encounters. Will there be higher-end areas where players will be able to find challenging high-risk, high-reward opponents to fight without having to play a lot of dull battles against weaker opponents? Playing against lower level AI decks is not very interesting and I don't know how long the PvE areas would sustain my interest if I had to run through a bunch of filler fights to find anything worthwhile to do.
Quoted from Zanzarino:
AI0 like deck in level 0-10 areas
AI1 like deck in level 10-20 areas
AI2 like deck in level 20-30 areas
AI3 like deck in level 30-40 areas
AI4 like deck in level 40-50 areas
FG like decks in level 50-70 areas
So yes, there will be a zone for FG difficulty matches.