[2021] Last Epoch’s next update is getting closer and closer and it will bring a lot of new powerful unique and set items for you to hunt! Here is just a little taste of what you’ll be able to find.

There are vfx showing the range while you have the shield equipped. It's the same range as the bubble for the "less damage taken from distant enemies" mod for rare enemies.

When does an enemy count as in that range? When its center is in that range?

No, it's measured from roughly the edge of the enemy, so larger enemies especially can count as nearby even if their centre isn't that near the circle.