If one word describes Blackwargreymon X, it is defence.
Blackwargreymon X , or BWGX in short, puts immense pressure onto your opponent's board. Like Magnamon X it can redirect an attack to itself, and similar to Dexmon it will delete your opponent's lowest cost Digimon during the start of their turn. These 2 effects together stresses your opponent's board as they will need to put up something larger than 13000 DP just to overcome BWGX, but will be deleted the next turn if they spend all their resources on that building that 1 Digimon.
Though many would believe that it is possible to bypass BWGX's first effect as long as they attack with their lesser DP Digimons, this can be circumvented when BWGX inherits [BT8-064] Greymon's [Blocker] effect.
Correctly built, BWGX will block 2 attacks every turn, which in many cases will be all your opponent can pull off. And 1 of your opponent's Digimon will always be deleted at the start of their turn.