The Eater of the Dead: How do I stop it?

[Lungfish]

Hello, everyone. I was just wondering, HOW IN THE **** DO YOU STOP IT!?! Sorry, let me do a brief play by play.
1. I summoned The Eater of the Dead, thinking how cool it would be to have a rampaging monster that attacks my foes.
2. After reading the description, I stupidly think how cool it would be to give it artifacts and cast Gift of Reason on it.
3. I VERY stupidly give it Nethgul the Starspawn and the Ark of the Covenant
4. I empower with level 3 astral magic to let it teleport.
5. I teleport it to a corpsey battlefield and let it eat
6. I watch as it digivolves into a giant monster and make it my prophet...
7. I then watch as it goes mad with power and obliterates a 125 point mage and blessing heavy militia and a fortress.


So, I was wondering, if I hadn't given it all those artifacts anyway, how do you defeat the vanilla Eater of the Dead?
Cuz it appears to be decimating everyone on the maps' armies.