Looks like Afterthought is going to take on the Justice League single handedly.
JUSTICE LEAGUE OF AMERICA #20
"SURGICAL STRIKE" finale! As Vixen and Prometheus' battle reaches its climax, Afterthought goes toe to toe with the Justice League in the most disgusting and dangerous place in the universe-the inside of Lobo's body! Will the League be able to defeat Afterthought in time to save Vixen? Or will Prometheus prove once and for all that Justice is hollow and the League is destined to die?
I think Spidey will win after a decent fight. I honestly don't really know much about Afterthought. I know Afterthought only upside is his precognition is better than spider-sense but Spidey has his strength, durability, speed, and reflexes going for him. Afterthought's base stats is a normal human with superhuman stamina. That's not quite enough.