I know The Endless mostly run on implied power, but what is Dreams best actual feat?
Since MJJ...wasn't there a weaker version where it took the destruction of a universe to take him out? Then the 616 version was only defeated when brought to place where there was no reality at all, and thus his reality warping didn't work. The thing that did it was the Fury, a robot that had actually survived the destruction of a universe(though not fully in tact).
On the other hand it might not be possible to outright defeat Dream in his own realm.
__________________ Chicken Boo, what's the matter with you? You don't act like the other chickens do. You wear a disguise to look like human guys, but you're not a man you're a Chicken Boo.