The armored figure continued to walk toward the group as they made their preparations. He was about 15 feet away when EMily spoke to him, and when she did, he stopped dead in his tracks. "Emily...I can't fathom the odds. But maybe...the gods are kind..." the man said, his tone altering to be less booming. As he stopped and spoke, however, the mist surrounding him continued forward, rising up like a tidal wave to crash over the group. Unfortunately, unless anyone was particularly fast enough to move backward and away from the wave, no amount of protection, magical or otherwise, would shield them.
Seras might have been fast enough, but she was standing toward the front of the group, and was therefore one of the first to be consumed. As the cloud covered her, the group would almost immediately start hearing her muttering in confusion, then screaming.
"Well fuck." Yorick said as there was no way for him to avoid the cloud and he suffered a similar fate.
Anyone consumed by the cloud would experience their greatest fear (I'll leave the specifics of that up to your individual discretion. How much detail you use is also up to you).
Except for EMily, who wouldn't be touched at all. At first a bubble would form around her, and she would be surrounded by the red mist, then a tunnel leading out materialized in front of her.