Godot. Thanks! I'll try to be more specific. This is how I think it can be:

Plant spawner knows what are possible plants to spawn in specific area and their base spawn chances. 

There is a list all active baffs and effects at this point.

Plant spawner asks what are active effects that affects possible plants to spawn and gets those modifiers. 

The rest is pure mathematics.

I really stuck in understanding on how to implement this effect entity. Should it use tags or different groups of tags. Or something else.

Cause, let's say we have effects

+10% oak tree

+5% broadleaf trees 

-5% broadleaf trees at night 

+3% sell price (not used in this situation)

And many more coming from weather, current altitude, moisture, season etc.

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