The iron crawler’s stampede combined with the tarantulas’ sticky web entangle is the tactic from the second floor.
On the deeper floors, Mad Skull joins the fray, and they give out commands while using rock bullets.
For Paul and the others who were having a hard fight on the second floor, I'm sure these tactics were severe.
Despite fighting with all their might, they should have had no leeway to search for Roxy at all.