[-] [+]

Possible Mechanics:

{w}{w} {w}{u}
{u}{u} {w}{b}
{b}{b} {u}{b}
{w}{c} {w/u}{b}
{u}{c} {w/b}{u}
{b}{c} {u/b}{w}

Past cards:

­{w}{u}

­{w}{b}

­{u}{b}