While I did fight against 200 Reapers, they were mostly Wraiths. And I basically just shot them all to death. However, the three Chasers had no such advantage and went up against 200 Summoners.
Depending on how many they summoned the Chasers would have been even more outnumbers. Neither Herman nor Carlos mentioned of the ranks of those involved in that battle. A quick look at the fear in the Specter's eyes tell a different story, however.
It probably went beyond just the difference in ranks. As someone who fought with similar odds, the sheer grit needed on the side of the Chasers would have been incredible.
And hearing about the result of that unyielding will, it must have manifested either as inhuman brutality or terrifying cruelty. Otherwise, the "trauma" evident in Carlos would not make sense.