Artifacts in Heroes III.

I was playing online once. Of course, I chose Necropolis, and my opponent chose the Human faction.
We agreed to explore the entire map together, and then decide the outcome with a single battle using our strongest heroes. And that's where I made a mistake!
We exchanged items: I gave him armor for the Alliance, and he gave me something for the archers and armor for the Cursed Ones. We each gathered our artifacts and went into battle.
My stats were higher, and I had a larger army.
BUT! That damned prayer ruined everything for me! I didn't even know how powerful it was.
In short, I was completely wiped out!
That's what happened. The Alliance of Angels is the king of artifacts!

Added 6 minutes later
As for the Shackles of War, I disagree. It's certainly useful, but only in very specific situations! It's a secondary item, and not even the best among them. For example, the Golden Bow is much more useful.
Honestly, the Shackles of War are only needed to steal artifacts. And it's not a guarantee that they'll be more useful to you than to your opponent. A player with good artifacts will always have a good army.