some info (spoilers)
Rats will always face the blue rat, if a rat is standing it means that rat is on the same collom as the blue rat. The blue rat cant be on the edge of the grid and will always have 4 normal rats next to it. when the blue rat is killed it will drop a scroll that will reveal the location of all rats
The purple wizard will always be on the edge of the map and will be always surrounded by 5 big slimes. when killed it drops a scroll that reveals the location of all slimes.
The necromancer will always be in a corner space.