Now that I've had some sleep, I use Amalj'aa as the bait card. It has about the same success rate as using Frixio as long as the AI takes the bait. If you start, place Amalj'aa at top center and use either Memeroon or Fruxio to take it back if AI falls for the bait, after that you'll have enough Ascension to not have to worry and just play accordingly. If the AI starts, place Amalj'aa in center left if he plays a card in top center or center right or if he plays Gaius in bottom center place Amal'jaa in center right.

Winning with a full beast tribe deck is really easy as pointed out and you can probably work out dozens of strategies that work very well. It took me about 7-8 hours to earn ~50k and all those cards in the picture so I would wager he is by far the fastest and best NPC to grind for MGP if it's what you are after. I also made a fair amount of mistakes (really, try keep focus and sanity after playing the same guy with the same strategy for 6hours and you'll start to make silly mistakes). But even then 9 out of 10 messed up games will end in a draw and you still make more MGP than you spend to play him.