Hyena

A hyena ally is unusual outside of three setups: a gnoll-friendly NPC has lent the party her pack, a ranger has taken Beast Master with a hyena chosen for the cackle, or the druid has wild-shaped into one for scouting. All three live or die on the noise. A hyena in town is an alarm bell; a hyena on the road is a question the next innkeeper asks pointedly.

In combat, the hyena chases and bites. Speed 50 means it gets to whichever fleeing enemy the party calls out, and one improvised bite at +2 for 1d4 will at least force a check from the wounded bandit. It cannot tank, it cannot grapple, and it cannot fight anything bigger than itself for more than one round. Use it as a runner, a flusher of cover, and a tripwire for ambushes the party walks into. Passive Perception 13 plus Darkvision 60 is the actual mechanical contribution.

Outside combat, the hyena follows the loudest food source. Train the players to feed it before they ask it to do anything, since the relationship is transactional and the hyena knows it. Have it growl at things that feel wrong (necrotic auras, charmed NPCs, hidden pit traps) and trust the party to read the growl. If the party loses the hyena to a single bad fight, that's the system working as designed. Roll up another one in the next gnoll camp.

Give the hyena a stupid name. The party will use the stupid name in their last words, which is exactly the tone you want.

A single hyena is a CR 0 nuisance with 5 HP, AC 11, and no listed actions in the SRD 5.2 stat block. The encounter design assumes a pack. Three hyenas are a credible threat to a level-1 party, six are a story, and any number of them are usually accompanying a gnoll warband. Run the hyena as the gnoll's hunting dog: it shows up first, harasses the flanks, and dies in one or two hits while the gnolls close.

Speed 50 is the headline. The hyena can dash 100 feet in a turn and still have its action, which means it picks a target, runs in, bites, and is gone before the fighter's reaction trigger settles. Without explicit attack actions in the SRD 5.2 block, run the bite as an Improvised Attack at +2 for 1d4 piercing, or pull the legacy hyena bite of +2 for 1d6+0 if your table prefers. Either way the damage is trivial. The hyena's job is to occupy the wizard for one round so the gnoll archers get a clean shot.

The pack moves as a flock of birds, not as a coordinated unit. Hyenas are Int 2 and operate on smell, sound, and the lead animal's commitment. If one breaks for a target, the pack follows. If one yelps and runs, the pack sometimes follows that too. Use the unpredictability to make the encounter feel chaotic rather than tactical: roll a d4 each round to decide which target the lead hyena focuses on, with one of the results being "the thing that smells most like fear", which is whoever just rolled a 1.

A pack scatters once it's been halved. The remaining hyenas slink into the brush and circle, waiting for the gnolls to catch up. If the party finishes the gnolls first, the hyenas leave and don't come back. They're animals, not soldiers.

Open with the laugh, not the silhouette. A hyena laugh in the dark before the party sees anything is the audio cue every table understands.