The quick and dirty prototype is working 
(still needs to add damage to the bush, so it can be destroyed when burned out):
It works as I desribed above, but I’ve added the first collision object that detects if there is existing objecy, and then it is disabled and the second collision object is enabled ti check if it can be ignited. It’s not perfect, so I’ll probably think about implementing the grid for bushes and grounds, but remain with a solution that the mobs will have their own particlefx triggered if it’s state will be changed to “burning” - it works like that:
P.S. Is it looking ok?
