“Two Seasons: Summer-Autumn 2015” Tournament. Online games for rating (reports, discussions).

Apparently, they were guarding the entrance to the treasury ;)

No. The Horror Riders 10-19, Mighty Gargoyles 20-49, and Monks 20-49 all guard the passage immediately after exiting the spawn point, and this passage leads both to the computer and to the treasury. Additionally, 50-99 Lizards (specifically, 78 with an improved stack) guard what appears to be another treasury. After examining the map, it's clear that it wasn't just poorly generated, but also contains bugs.
In short, immediately after defeating the guards and exiting the spawn point, it becomes apparent that there's nowhere to go except to fight the 78 Lizards or the 10-19 Horror Riders. The latter are clearly bugged and positioned directly after the elevator on the road in the underground.