Unholy Strength
This card have had an interresting destiny.
The original art in Unholy Strength featured a pentagram, but reprinted versions had this pentagram deleted. The reason for this is that Christian Groups were starting to complain on how MTG was introducing young defenseless minds to the influence of the devil. They caused enough of a stir that WOTC also stopped producing creatures of the subtype Demon for several years.
Unholy strength is remarkable on one aspect. That it is the only card in magic where the art has been changed due to public demand.