Though the moonscar is wholly located on the Martial Plane, the entire region shares a number of qualities with the Abyss. Unless noted otherwise by me, all the following planar traits are in effect once you are on the moon and for the remainder of the adventure. More information on these planar traits can be found on pages 184-188 of the GMG.
Strongly Chaos-Aligned and Evil-Aligned: Nonevil or nonchaotic creatures take a -2 circumstance penalty on all Intelligence, Wisdom, and Charisma based checks in the Moonscar. This penalty stacks with itself for creatures that fall into both categories, resulting in a -4 penalty for creatures with alignments that are neither chaotic or evil.
Enhanced Magic: Spells and spell-like abilities with the chaotic or evil descriptor are treated as if their caster levels were 2 higher than normal. Additionally, because of millennia of influence by the Insatiable Queen and her mistress Nocticula, the save DCs of spells and spell-like abilities of the charm and compulsion subschools increase by 2, regardless of who casts them. This increase stacks with other methods of increasing a spell's save DC (such as the Spell Focus feat).
Extraplanar Natives: The Moonscar is home to many extraplanar outsiders, including the succubi who rule over the demonic jungle. Such creatures receive a +4 bonus over the demonic jungle. Such creatures receive a +4 bonus on saving throws made to resist being banished back to the Abyss, as their affinity for the Abyssal jungles of the Moonscar binds them strongly to the Material Plane.
Impeded Magic: To cast a spell or use a spell-like ability with a good or lawful descriptor, a caster must make a concentration check (DC 20+ the level of the spell). If the check fails, the spell does not function but is still lost as a prepared spell or spell slot. If the check is successful, the spell functions normally.