Weretiger

A weretiger ally is the most plausible non-evil lycanthrope to put on the party's side. Lycanthropy is alignment Neutral here, which means the weretiger is a person, not a monster. A weretiger can be a ranger from a tiger-clan culture, a former NPC the party rescued from a curse-broker who weaponizes the change, or a guide hired in a jungle frontier where weretigers are normal residents. Treat them as a competent NPC who happens to have a curse.

Negotiate the ground rules in scene. The weretiger does not bite party members. Ever. If a fight goes badly and a PC drops, the weretiger does not bite them to "save" them, because the curse is a fate worse than death by their own culture's standards. Make this an explicit conversation early. The trust is the relationship.

In combat the weretiger is a flexible second front. Hybrid form gets two Scratch attacks at +5 plus Prowl as a bonus action, and 120 HP at AC 12 means they soak hits the rogue can't. Use Prowl to flank: move 30 ft. to the enemy's back, Hide on the same turn, grant the rogue advantage next round. Save Bite for non-Humanoid enemies (constructs, undead) where the curse doesn't apply, or against a clearly evil Humanoid the party has already decided is going to die.

Out of combat the tiger form is a Stealth +4 scout in wilderness and a 40 ft. mount in a pinch. Hybrid form scares civilians into windows. In tiger form the weretiger can't speak Common, so the party loses their negotiator if they send them ahead.

When the campaign moves on, the weretiger goes back to the clan or the jungle. Have them show up later as a reference: the players' actions in the city reach the weretiger's people, and the weretiger reports back to the party with consequences attached.

A weretiger is a hunter, not a brawler. CR 4, AC 12, 120 HP, and a Bite that curses Humanoids who drop to 0 HP into new weretigers under the GM's control. The high HP at low AC tells you the encounter is meant to be attritional, and Shape-Shift plus Prowl tells you the weretiger picks when the fight starts and where.

Open in tiger form, from cover. Stealth +4 plus Prowl as a bonus action (move full speed without provoking opportunity attacks, then Hide at the end) means the weretiger gets one ambush round before initiative settles. Multiattack is two Scratch (+5, 10 slashing each) or one Scratch and one Bite (+5, 12 piercing plus the curse on a failed DC 13 Con save). Tiger form has Walk 40 ft., which lets the weretiger cross the room, hit, and Prowl back into shadow before the party's caster gets a turn.

Use Bite on the PC most likely to drop to 0 this round. The curse is the encounter's lever. A PC who fails the Con save is cursed, and if they hit 0 HP later (or in the next fight, since the curse persists), they become a Weretiger NPC under the GM's control. This is a horror beat, not a routine outcome. Telegraph it through a previous victim the party finds half-changed, or through the weretiger's own taunt before the bite lands.

If the fight goes long, the weretiger Shape-Shifts to Hybrid form to use the Longbow at 150/600 ft. (+4, 11 piercing) and pulls back to range. 120 HP at AC 12 is a lot of soak time for a tier-2 party to chew through. Once Bloodied with no clear path to a kill, the weretiger Prowls into shadow and breaks contact. They live to hunt again.

Have one cursed NPC in the lead-up to the fight: a hunter who's been twitchy for three days, a child who keeps eating raw meat. When the weretiger dies, the curse on living victims persists. The cleric's Remove Curse is the answer, and now the party has a reason to find a cleric.