Design your opponent, (it's a button on the home screen.)
You may choose all aspects of your opponent! Hp, card draw, number of marks, and wether they have upgraded cards or not. The cards they use are like AI4 but the standard reward you get starts at elder lvl. As you increase their HP, card draw, and number of marks you're reward will increase at a double or triple loss of score and electrum. So if you kept it the same hardness as ai3, and won you'd gain ~40 electrum and ~30 score as opposed to winning ~20 electrum. If you lost however, you'd lose 30 score as opposed to 10, and lose 30 electrum opposed to losing 10. Dare accept your own challenge?
Reward: Increase of HP by 50 means 50 more reward. It continues like this in chucks up to 1100. The number of marks will increase your reward by 10 for each above 1, up to 5 cards drawn per turn. If they have upgraded cards your current reward will change by + half of it.