Vermintide 2's difficulty mirrors MMO raids more than Left 4 Dead's hordes

Warhammer: Vermintide 2 sold over 500,000 copies in its first week of release, and it is probably safe to say that the majority of its players are very happy: it is a fantastic game. But it is also rather different to its predecessor. Yes, it is still a game about hacking the limbs off giant rats, but there is something new here. While the original game felt like Left 4 Skaven, Vermintide 2 is akin to a Warhammer-themed MMO raid. 

Vermintide 2 is hard. Like, really hard. The torrents of Skaven scrambling over each other to tear you apart with tooth and claw feels relentless, even more so than in the first game - and this time they are backed up by stronger, hardier Chaos forces. More often than not, these packs of enemies are reinforced by deadly special units, too: the noisy Ratling gun, the Gutter Runners who can incapacitate you in a single leap, and Rotblood sorcerers who trap you within a swirling tornado of lurid green magic. 

from
https://www.pcgamesn.com/warhammer-vermintide-2/vermintide-2-mmo-raid