Spawning new tiles

[Emera Nova]

So I'm currently attempting to make it so a certain creature spawns in lava tiles under it as it walks around.. The biggest issue I'm having right now is making it only spawn 1 of these tiles in and not stacking if its moved back on top of an area its already been on. (The burn damage ends up stacking due to the tile being placed a second or third time.) On top of that it also creates more particles that dont need to be there.

Any suggestions for what Im trying to do here?

[zimberzimber]

You could check for objects in the tile its about to spawn lava before it does.
I can't really give you the full function for checking right now because I'm on the phone, but the green herder in my asset pack uses a similar function for when spawning poison clouds while moving.

[minmay]

Use Map:entitiesAt() to see if there is already a wall_fire object there.