Languages

Think about what languages the creature would need to communicate with other creatures in its home. For instance, many intelligent undead speak Necril, and many creatures from the Azlanti Star Empire speak Azlanti. If you want your creature to be able to speak to the PCs, be sure it has Common; for a creature with no reason to speak the common tongue of your setting (such as most extraplanar creatures in a typical campaign, or creatures from the Vast), be sure it doesn't. Some creatures can understand language but can't vocalize; in this case, you can state that they can't speak any language. For creatures that need to be able to infiltrate and communicate wherever they go, you might give them a digital translator, truespeech, the ability to communicate telepathically, or a similar ability as a constant innate spell.