Greater Dog is one of the many Taunt monsters. Previous versions can be seen here.
This card has high HP, like Gyftrot, having 2 less HP then this. The main purpose of this card is so you can place high ATK monsters like Royal Guard 2.
This is great with Kindness spell cards like Longevity, Heal, or Force of Nature. It also works well with Asriel in case it has low HP or this card loses its Taunt. This also works well with Asgore, making monsters being damaged.
This can be countered easily with Penetration by removing its Taunt. It also countered easily with Madjick.