It's a truly monstrous amount of flaming destruction on a massive scale, devastating the people of the eastern European nation of Symkaria and emotionally crushing its champion, Silver Sable. Spider-Man's determined crusade to stop Dr. Octopus' last grand plan has failed epically, resulting in the flash-frying of the entire hemisphere, sending Spidey's small commando unit reeling into despair and panicked argument. How in the world can they bounce back from this?
It helps to realize that the bad guys are sporting a true master of illusion.
Mysterio has always been my favorite Spidey-villain, as you have to respect the fishbowl, and Amazing Spider-Man #686 puts the focus on Quentin Beck, the special-effects maven turned to crime, and his amusing relationship with Chameleon. It makes perfect sense – both are masters of their stagecraft, one behind the scenes, the other as a thespian writ large. The apparent destruction of Symkaria simulating the end of the world is Mysterio's greatest special effect ever, and he revels in it by having the Chameleon don a fake Doc Ock suit and taking the fight to Spidey, Sable and Black Widow, intending to keep them occupied and distracted while Octavius does his thing. Only when Ock discovers what Mysterio is doing, he flips out angrily, claiming he will not have his duel to the death with the wall-crawler waged by proxy. And that's when things start to fall apart.
And that's when things also get interesting. When Spidey figures out the illusion, Natasha cows the Chameleon, and then makes a pitch to the master showman that he can't refuse, leading to a completely unexpected and fun Spidey-Sterio team-up. The motivation is a smidge sketchy, since it doesn't seem like Beck is dumb enough to have not considered the fact that his two-billion dollar payoff amounts to nothing if Ock actually does decide to torch the world, but even though he's apparently selling Ock out, his loyalties are still entirely dubious and mostly to himself. Thus, it still works… and it's entirely possible Beck's led them right into a very impressive trap, to boot. Topping that, we STILL don't really know what Ock's endgame is, and the intrigue keeps growing.
I can't say enough good things about Dan Slott, and you've heard/read them all before anyway, so I'll just say he's still kickin' it with the densely packed and entertaining scripting, while Stefano Caselli's art is plenty great, too. Amazing Spider-Man #686 is good stuff, and anything that makes you actively root for Mysterio is welcome in my book.