Of the many times I've been shot by the Adversary's homing Brimstone, I've managed to avoid it just a couple of times. So, I know it's avoidable, but I don't know how to do it reliably.
Usually when I get there it becomes a power check: if I can dispatch him before letting him shoot his first Brimstone I have good chances to end the run victorious. The problem is I'd like to have a chance to end even those runs when I have less firepower, but usually in those cases if I get the Adversary my run stops there.
Best Answer
The Adversary picks a direction to shoot, then charges up, then shoots. And the homing only goes so far. When you expect him to fire that brimstone, just do a quarter turn around him. Or you can constantly move, circle around him without stopping, and the shots won't get you.
A video that kinda shows this