In the TODG Throne of Corruption (where you protect the throne from corruption and aim the hulks at the throne), the Corruption Meter in both stage 1 AND stage 2 increases based on enemies merely appearing in the instance, not by their interaction with the two clerics.
So, basically the timer for stage 1 is 5 minutes, and by the end of 5 minutes you are guaranteed NOT to have any ranking at all (not even a bronze). As you kill the enemies, more appear and the corruption meter increases.
In Stage 2, it works the same way, except that the meter increases even faster than in stage 1 (which is the opposite of the intended affect).
LEVIATHAN--19.3k Metallic Dragonborn Guardian Fighter Swordmaster Loadouts
Guild--And the Imaginary Friends