Each of your opponent's monsters that conducted an attack while this card was face-up on the field has its ATK halved as long as this card remains on the field. During each of your Standby Phases, pay 2000 LP or destroy this card.
I feel ya. Same thing happened to me. I got mirror wall after like 180 packs and then reset the box. I'm now only 50 packs in and I haven't gotten a second one yet. I really don't want the same thing to happen again.
I have 3 senju, 2 ganlordof, 2 black pendant, plus one of each UR, without count tons of SR, so after reset, the thing was, I spent 80% or more the gems I got since I started to play this game, trying to get a MW, was so frustrating to get, that many times I reseted the box when mad... But finally got one, now I need ideas about decks, because basically all my cards are from this pack