Saints Row: Gat out of Hell
45 Achievements
20-25h
Plague of Gat
Kill 1000 Demons with any combination of Supernatural Powers
3.1%
How to unlock the Plague of Gat achievement in Saints Row: Gat out of Hell - Definitive Guide
Basically once you beat wave 3 of a tomb, instead of going back to the tomb to finish, you can stay in the area and get kills on what stays as a level 2 notoriety, which means you'll get an endless spawn of regular enemies to play around with.
When you're done farming kills for the session, you can always just leave the area or complete the tomb mission if you have more still available.
This trophy is earned for killing 1000 enemy Demons with your supernatural powers. This will most likely be one of the last trophies you earn, as this only counts against hostile demons. Killing husks with powers doesn’t count toward this trophy.
While working on the challenges for each power you will get the majority of the way to this trophy, but if you do have to grind kills I suggest running around with the Holy Stomp power and just spam it in groups of enemies. When it’s upgraded it will one shot almost everything, so you can easily take out large groups of enemies with each stomp. It also doesn't cause vehicles to explode which can take away from your number of power kills.
Using ANY combination of powers. So you can combine effects i.e. petrify enemies and them smash them with stomp. You can also just kill enemies with a singular power. You will get this achievement grinding out challenges.
This method comes from forum member osakamitsu
In the bottom left part of the map there is a building that is guarded by demons. There is a vertical street that divides Azazels Court and Seers Tongue, that is where this building is. Go to this building and start building notoriety, this building has fast and infinite respawns. For the sake of quickness and spawn rates, makes sure not to kill the demons that float around in a bubble. They summon more enemies. You can farm all kill types for all achievements and challenges this way.
Important: all types of demons count, except sinners.