I'm not sure that's for the best, really. If you write him that way, he's like 9,001 other villains who have no depth, just
"Hey, I just met you
And this is crazy
I really hate you
So let's fight, maybe?"
I mean, at least if he's protective of his fellow monsters - even if it's for some selfish reason, like he enjoys lording over them - it at least gives him a motivation. He's less cookie-cutter that way. The whole thing, including sacrificing his minions, would make sense if he had some other way to screw your economy other than killing his own minions. Maybe if he and the monsters were seizing gold mines. Or, in a very goat-like move, were trying to starve you out by eating all your grass. Without grass, then several farm animals couldn't be easily fed, which reduces both grown food and food from slaughtered livestock, so just being a goat very aggressively at you would work. It's just this exact combination of factors that's perplexing, currently.