Your constitution score increases by 2 and another score of your choice increases by 1.

Your innate ability, as well your fiendish influence, have given you some boons in life. You are immune to any side effects or damage that may occur as a result of smelling any noxious fumes or foul odors. Additionally you have resistance against any poisons or other toxins you ingest.

There are some benefits to being a gnoll.

Your senses of smell, hearing and sight are legendary.

Whilst listening you gain proficiency in perception checks.

Your sense of smell is immeasurable. When you roll an investigation check using your sense of smell you gain proficiency. When tracking a humanoid using your sense of smell (survival) you gain double proficiency in this skill.

You have darkvision up to 60 ft. When you roll for initiative, and are not in direct sunlight, you gain a +1 bonus.

Your people have a knack for repurposing discarded detritus, organic or otherwise. Perhaps you made a bow and arrows from the remains of a recent hunt. Maybe in a large city you find abandoned materials to repair your armor. Whatever the case may be, you have an innate ability to reprocess what would otherwise be trash into useful items.

Choose one of the following tool kits to be proficient in: leatherworker's tools, smith's tools, tinkerers tools. You use these tools to aid in your scavenging. You have customized these tool kits to fit your needs, be they varied or focused. 

If there is one thing a gnoll is known for it is their powerful bite. You have the ability to crush someone's neck, in your maw, without piercing the skin. Your bite is a natural weapon, which you can use to make unarmed strikes. If you hit with them, you can deal bludgeoning damage equal to 1d4 + your Strength modifier. You can also crush the bones of a creature large size or smaller.