A way to bring the sunlight/moonlight from the elven world from the portal, the light would affect blocks/plants in a radius of the portal in different ways, or it could be focused using mirrors (that would work like the mana spreaders but mostly made with alfglass and lens) to be directed over longer radius, moon light and sun light would work differently from each other, you would have both from the same portal at different times...

Dropping this idea here if you want a different concept for creating end stone for example :)
I had this idea a little while ago for a overgrowth concept but I got shy to post over here, in the end i like the overgrowth seeds to be better since its something rare.