It is like the doom card EXCEPT it has more requirements and your opponent can do something about its effect. Im sure a lot of players want it because of the popularity of the darkus bakugans.
1.Its not THAT rare.2.Effect is VERY good.Its kind of like a trap type thing,where if you win,then they cant use that bakugan unless they sacrifice a gate card,which would let you get two gate cards.
Once the player returns the gatecard it then goes from his USED pile to his UNUSED pile. It does not move the gatecard to your used pile. It is a good stalling card since your opponent may be forced to give up one gatecard he/she has won already.