This is something else that didn't really make sense. Styx is performing a spell to reach out to Garanos in order to figure out what happened down in the tunnels, and the influence of the magical energy is what tips the scales in favor of the Harbinger; he feeds off the invading energy and is able to manifest himself. But the way I actually sequenced it out here makes it look more like Styx purposely entered Garanos' mind to set the chain in motion. And that's definitely not Styx's style.