Have you checked if there are spells with similar effects that you can look for inspiration?

Remove radius or set it to 1 or 0. The modifier is right, it should work. Show your entire spell if it still doesn't.

hopefully you upload it when your done, im looking at making a few spells that add resources when cast (trade mana for crystals or mana for horses essentially), which is different than spawning a thing within your radius. I like your idea, and I hope you upload it when your done.

It would really compliment my Mythic Buildings Pack 2 (which will specialize on buildings that add Wargs, Horses, Metal, etc.)

So far the only problem is the in-game graphics for the actual map icons are "big" and I need them "small", so for now I have them tied to stupid stuff like Garden and Apothecary.

Can Arcane Monolith be "rewired" to "Crystal"?

Post your code and I will see if I can make something work. I can't guarantee it will work but if it does,  we will all have more fun because of it. Especially if the AI can use it. I would like to see such a spell for mana shards, just me.

There is also that spell that converts an existing shard...  maybe it can be "parted" down into something that can work with part of the arcane monolith code?

Have you tried to skip creating "Crystal" on the map, and instead create the lowest level improvement which produces crystals?

My last idea would be to copy-paste text from Outpost and Improvements, and see if an Arcane Monolith spell can be wired for the task. (Outpost gives nothing, with additions which can be built that add resources).