I agree with the need to have greater rewards and resources in harder levels. Another thing that bugs me is that the info at the bottom of screen blocks off placement tiles in some levels.
In browser, there needs to be a means of distinguishing between cards kept in the deck and spares, making tearing up cards more efficient. Stacking would make things clearer, too.
Dismissing members of the team will give you items.
L10 = random berry or white egg
L20 = random blue egg
L30+ = random green egg
Each time you take a castle you get a skill point. Use the earliest ones to rush the skill where all new recruits start at level ten to farm for eggs. Later in the game new recruits level fast.
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