Isbellele should be able to draw a card even if you have 0 in deck?

[Imm0rtaleflame]

Now it makes no sense to play it for card advantage
2 rounds combo with the guy who sets opponents card on top. Set own top card. Then zeal. It doesn't quite work

 

[FG15-ISH7EG]

I don't understand what you are trying to say.
Though, if 1 player has 0 cards in deck and Isbell is used, the player using Isbell gets 1 card and the enemy 0 cards. Thus, she can be used for card advantage in that scenario.

 

[monkeypony]

Nope.

Isbell doesn't work if your opponent has an empty deck.