The Half-Moon Colt was intoxicated by its newfound ability, but Gaven was not.
The fact that the God of Corruption and Degradation's followers appeared on the outskirts of Mesnoel indicates that the Necrotic Mystlock Lock there isn't simply out of control.
It is very likely that these cultists did it on purpose, as for the goal.
The specific goal is hard to guess, but the ultimate goal is always the same.
That is to honor their own deity and obtain even greater power.
Considering the God of Corruption and Degradation is in a demigod ruined state, these cultists are most likely trying to revive their deity by all means.
Valon, the Grand Inquisitor, approved of Gaven's speculation, "Unlike other evil god's followers, all of Moando's servants can be considered an extension of Moando's will. Though it can't manipulate its servants as freely as when it was alive, its influence still persists.
They have only one purpose now and forever, and that is to revive Moando."