Harry Potter "detention"

[Thanla]

I am in doubt about this card

This card reads:

Play when another player is about to go up a lvl!

Send them to detention and i stead you go up a lvl. Cannot be the winning lvl.

So my question is:
I fight a monster granting 2 lvls and 4 treasures, and my opponent plays the detention card!
What happens, does the opponent steal 2 lvls or 1?
And if 1 lvl, then what happens to the remaining gained lvl?
And what about the treasures?

[Mr_Draco]

The card says nothing about treasures so those don't change, just the levels.

The card only says "a level" so in this case it would be 1 level while the player who won would get the other.