I finally defeated lord bot on my third attempt. I was offered the chance to purchase him for 300 gems instead of 500. Figuring how much I liked the elite battle arena (started playing it before I beat lord bot, currently at the 4th rank!) I figured it was a good deal and I could buy two more arena runs.

I clicked purchase. Bought the gems and then... I got 500 gems and no lord bot. What happened?