I spent all weekend developing a deck that would win 80% of the time against level 5 in the trainer. It worked. I spent nearly 2K building my deck and it has lost ~ 98% of the time against level 5, 80% of the time against level 4, and 60% against level three. Is the trainer AI so weak that one can't actually use it to test decks?
It very frustrating to get a deck together, have it win there, and then discover that at best, its a middling level 3. Especially as I spent nearly have of my cash reserves on it.