The Attack Dog spell causes the target to behave like an attack dog.
Rowena later used the spell on three angry college students in an attempt to kill Dean, but the attack failed. She then leveraged their lives to force Dean to let her go.
Rowena later cast the spell on the Seraphim Castiel, making him attack Crowley. After apparently killing Crowley, Castiel regained control of himself, but remained under the spell's effects. Apparently due to Castiel's nature as an angel, the spell couldn't take full immediate control over him and instead started "digging deeper" into his being. This resulted in brief fits of uncontrollable rage that quickly subsided. In one of these states, Castiel was able to use his telekinesis even while restrained by Supernatural Handcuffs, showing that the spell apparently overrode the handcuffs effects. The angel Hannah was unable to remove the spell nor heal Castiel's injuries while he was under its effects.
After a few days since the spell was cast, Castiel lost the red-eyed look the spell gave him, but still remained in a sickly condition. As the spell continued to dig deeper, Castiel experienced seizures where he had flashes of his actions under the spell and felt like he was a tomato salsa in a blender set to puree. The spell appeared to be trying to gain full control over Castiel by tearing at his being and Rowena indicated that he would eventually go "foaming at the mouth mad" and then die like anyone else the spell was cast upon. Eventually, the spell appeared to gain full control of Castiel at which time he regained his red-eyed state. Before the spell could do any further damage, it was reversed by Rowena.
The spell required a hex bag to be held by the target and an incantation to activate the spell. The incantation is as follows:
- Impetus bestiarum. (means "attacks of beasts")
As soon as the incantation is over, the target would appear to be overcome by pain. They would lose human consciousness and act, behave, and even sound like an attack dog. The spell causes the target's nose, and later, the eyes to bleed and for them to ultimately die. Rowena stated that the person is consumed by the spell but she is able to prevent this aspect of it if she so chooses.
In Brother's Keeper, Rowena was capable of using this spell without the hex bag. She was also able to affect Castiel, even though he is a Seraph, and forced him to attack Crowley. Additionally by using certain Latin incantations, it will amplify the rage and physical powers of any affected target to a certain degree, leaving even Crowley's fate to become uncertain. The following incantation is:
- Dele malum hoc (means, Destroy this evil (being))
Rowena broke the spell by reciting "Desiste, Adlevo onus tuum" (Stop, lift your burden) to Castiel. He shook violently, and fell to the ground. After that, the spell was revoked permanently from him without any adverse effect.