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You can clear the early stages by focusing on splash damage, shields, and supplies. When leveling up in-game, upgrade your dealers and focus on about two of them. Most stats like 'all attack' or 'all attack speed' are efficient even if they appear at a lower grade. (Don't blindly trust the ones with thumbs-up icons) Other than that, the game balance is pretty broken, with many mediocre or outright trash picks. As a side note, the game is quite unfriendly in many ways. 1. Dealers have different focusing levels. - Some dealers focus on the boss, while others attack randomly. You can't control this, and there seem to be no options for it. 2. Sometimes, dealers you haven't placed yet appear in the upgrade choices. - If they come with trash options, that round is hopeless, you gotta run. Keep this in mind, and don't bother trying to clear all hidden quests if you value your sanity, f***.