k if u mastermind damage to a mystic team ability character who takes the damage my piece using mastermind or the opposing attacking piece? can the damage be reduced by the piece masterminded too?

Questions about the rules of the game are better asked in the Rules of Combat forum, where the Rules Arbitrator and his amazing Deputies live and keep everyone honest. (You can tell them because of their fancy orange coloring!)

The piece you mastermind damage to is the one that takes the damage, and it takes all of the damage. This damage is not considered an attack (Mastermind says so), so it will not activate Mystics (which requires that you take damage from an attack). The piece that ends up with the damage can reduce it, if it has an appropriate power.