After playing for a bit, I gorra say, cool prototype. Wish there was more control over what units you get though, it's really hard to create combos and such. Maybe you could add some sorta "unit catalogue" which lets you fave/ban certain units to more easily get the stuff you want. Maybe you could fave three units, making them twice as likely to appear(still taking ranking into account ofc) and also ban three units, making them not viable to be drawn.