The most powerful thing in the diablo universe is.......
A puddle of poison.
That is correct, a puddle of poison.
As gods and demons wage their war on each other, this lone puddle sits still and waits as mighty magic decimates anything around it. After the victor has been decided and the mighty warriors of legend congratulate each other, this little puddle sits and waits for the unsuspecting fool to touch it. Death is all that will come of touching this little puddle, and their god-like power can do naught, when faced with a all powerful puddle of poison.
Don't be ridiculous. We all know what the most powerful thing in the Diablo universe is:
Powerful heroes can one-shot the most gigantic and powerful of all demons. But doors? Nope, one hit isn't always sufficient, sometimes those nasty obstacles withstand the first impact and demand a second attack.
Experienced characters plow through hordes of monsters like there is no tomorrow. No matter the type, size, or fierceness of enemies: barely in sight of the player, enemies drop to the ground, giving up their precious loot obtained from the siege of Tristram's neighborhoods. Nothing can stop them - except for... doors. I have seen it with my own eyes, witch doctors and necromancers stop their high-paced hunt in front of a simple door, charging up their spells and waiting for magical powers to be ready before continuing their crusade.
Doors are unmatched in their might and power. To settle this debate, I call for an eyewitness from another universe who knows all too well about the power of doors.