Here is how it works now.

You can only turf cast spells from the standard elemental wheel on improvements, namely palisades.

Palisades increase the fizzle rate of magic attacks.

As it is now, you can bypass the fizzle rate and the restriction of standard-wheel elemental spells by ctrl+alt clicking on an improvement so long as there is a PC/NPC standing on your target tile.

I suspect that being able to bypass the fizzle rate offered by palisades is a bug.

Gaku: addressed in update

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