The Grail – what is it?

I noticed another trick – the computer opponent starts “digging for the Grail” very early, and usually with a weak hero. If you notice where he’s searching, just eliminate the opponent and dig in the same area. I usually don’t waste time on obelisks…

But what if the computer has already dug up the Grail? If a hero with the Grail loses a battle (even if he flees), the Grail is lost :-(

P.S.: I think, like many others, I don’t care about the properties of the Grail. (Except for the Conflux and Tower Grails). The main thing is the stat boost and the extra gold!!!