If you have another monster out, use this card in conjunction with "Seal of Orichalcos" to create a battle lock.
This is a great card to bring back with "Dark Horus". With 1900 DEF, it's not going to get destroyed by battle easily,and even if it does, you can reduce the ATK of another monster down to the point where it can still offer protection.
"Generation Shift" is a good card to play with this card, by sending the selected "Ghost Gardna" to the graveyard its effect will allow one monster on your opponents side of the field to lose 1000 ATK giving you a chance to attack it with another monster and also summon another "Ghost Gardna" to the field.
This is a good card to use in a Venom stall deck, as its 0 ATK prevents it from being destroyed by "Venom Swamp", and its ability to make your opponents monsters target it protects the relatively weak Venom monsters.