Muscle Shriek

(This ability is active if you have one or more face up G units in total on your or G zone): 2 When this unit attacks a vanguard, you may pay the cost. If you do, choose up to two of your rear-guards, them, and they get +2000 until end of turn. :[ 1 & 1] When this unit is placed on , you may pay the cost. If you do, choose one of your grade 1 or less rear-guards, choose one of your opponent's rear-guards with less than or equal to that unit's , and retire it.