I've reported this before in a bug list but think it deserves it's own thread in case it was overlooked. It was never acknowledged anyways.

The spell seems to work less than half the time. It would make the shard disappear first then the next turn a death shard appears where the old shard used to be. Now sometimes you can build a shrine on the shard and sometimes you can't. The shard is there and can be clicked on and has an enabled build button but clicking on it does nothing. The strange thing is after a few turns it might be buildable. Or maybe after reloading a save or casting the spell on it a couple more times. Sometimes the shard is useless for the remainder of the game.

Maybe casting the spell on it while it is in the process of building a shrine or already has one built contirbutes to this but I have also seen the bug happen on a new shard that I haven't started to build a shrine on yet either.