Another way to understand, is this:
Say you have a weakened monster on your side cause of wall, which pretty much anyone has x2. With Potion you will gain LP equal to the nerf (-800 etc), but with Altar you heal the original attack points of your weakened monster.
is there any way to get this card now that the paradox bros are gone?
Were did they gone? They are at the gate. The card can be obtained by dueling them at the gate.
Just out of curiosity, I had a game where I used this card on a set Hiro's Shadow Scout (yes, it was a dirty mill deck BUT I was going against a Toons player) and was wondering why I didn't gain the 600 or so LP from my set monster's attack?
Is there some yugioh rule that I don't know about that says the attack of a set card is zero and since Destruct Potion doesn't take the attack of the monster while in the graveyard I got nothing?