Revenger, Phantom Blaster "Abyss"

:[Legion 20000]"Blaster Dark Revenger "Abyss"" :[ 2 & Choose three of your rear-guards with "Revenger" in its card name, and retire them During the turn that this unit [Legion], at the end of the battle that this unit attacked a vanguard, you may pay the cost. If you do, all of your vanguards. This ability cannot be used for the rest of that turn. (Even if you do not pay the cost, this ability cannot be used for the rest of that turn.) :When this unit attacks a vanguard, this unit gets +2000 until end of that battle.