EPIC idea. And we are totally keeping the name "Slave Market".
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To slightly fix Puppy's problem and make things a little more interact for the "slaves", why not let them have two special elements?
One Element is "Wanted": The player may choose to add 2 "cards" to target Master's bid. In the event of a tie, this element wins.
Another Element is "Preferred": The player may choose to add a "card" to target Master's bid. In the event of a tie, this element wins.
Example:
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has 9 cards on this guy.
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has 8.
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has 2.
The player "Wants"
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, so he adds 2 to it to make it have 10 cards. Whoopee! He also "Prefers" death, so it's 3 cards. Not that it matters.
How does that sound? Otherwise, I love this idea.