Please do not replace images on pages with lower-quality ones. There is no rule on RangerWiki that states images need to be .PNG files or have transparent backgrounds. It is not your place to enforce rules that do not exist. Consider this your final warning.
Admittedly, we really shouldn't have the descriptions of the MotW on the general MotW page because they all have their own pages now. If anything, the category pages should just be lists of the monsters themselves with links to all of them to direct to the actual information (what they did, powers, trivia and whatnot)