I've been thinking of trying out all bosses and I noticed that there doesn't appear to be anything in the rules about ghost wands. I asked about this during an Aliasbot stream and his response was that the consensus was that you're allowed to kill ghosts but cannot pick up the wand they drop. I would like to get some written confirmation on this and preferably an addition to the game rules if there are restrictions.

Being able to use the wands from ghosts would be an unfair advantage, since you can easily stuff your bones folder with perfect travel, boss killer, attack wands. It would mean we'd likely have to all use a fresh save to run the game, or a master save uploaded here so that everyone is on the same level field.

Letaali, Bard and Bonfire need to weigh in, as the current mods.

That isn't my only concern actually. Even if the player is not allowed to use ghost wands, they can still construct wands for their bones folder which are beneficial to the player when fired by the ghost. Additionally, the ghost enemy is easy to kill with the tablet and drops a large amount of gold relative to other enemies which can be encountered early, so even filling your bones folder with useless wands could give an advantage as it would make the ghosts less dangerous. Because of this is seems like the easiest solution would be to force an empty bones folder, which does not seem difficult to enforce as the run would only really be invalidated if a ghost enemy is encountered.

Simply banning the use of the ghost wand by the player is sufficient IMO. The amount of gold it gives is comparable to a gold pouch or a big chest payout, and would be silly to restrict. On the note of intentionally constructing wands that are beneficial when fired by the ghost, I think this is likely a bigger problem in theory than in practice, and taking steps against it by requiring an empty bones folder may be nuking a mosquito, so to speak.

I've added the ghost wand restriction as a rule to the categories where I think it matters the most: All Bosses, 11 Orb and 33 Orb. I think most runners have been of the same mind on the issue for a long time, it was just never added as a rule.