Manticore

A manticore ally is the gift of a wicked patron, a contracted mercenary in a cosmopolitan city that hires monsters openly, or a captured juvenile the party raised with food and conversation. The manticore is Lawful Evil but speaks Common, which means it negotiates, takes payment, and keeps a deal as long as the deal is profitable. It will not work for free. It will not work for a party it considers weaker than itself. And it will absolutely not be ridden as a mount unless the rider has accepted, in writing, that the manticore is a hired pilot rather than a beast.

In combat, the manticore plays its strengths from the air. Three Tail Spike attacks at +5 for 21 average damage hits whatever target the party paints. The manticore likes named targets and dislikes mooks; it will shoot the captain over the squad every time. Multiattack flexibility means it can mix one Rend on a flying enemy with two Tail Spikes on ground targets, useful in a layered fight. Fly speed 50 ft. keeps it out of melee range of anyone without reach or a bow.

The manticore exits when the contract is fulfilled, not before and not after. If the party tries to extend, it names a new price. If they try to cheat, it starts collecting in spikes. Pay it on time, address it by name, and it will work with the party again. Slight it once, and the next manticore encounter is personal.

Have the manticore quote its rate up front in gold per spike loosed, then count loose spikes after the fight. Players will pay the bill, then complain about it for three sessions.

A manticore is a flying sniper with a melee option it would rather not use. The stat block hands you both halves of the kit (three Tail Spike attacks at +5, range 100/200 ft., 7 piercing each, plus Rend at +5, reach 5 ft., 7 slashing), but the manticore that fights smart never lands. It hovers at 50 ft. of fly speed, well above the range of most martial weapons, and shoots tail spikes at whoever has the worst ranged answer. That is the encounter.

Open from altitude. The manticore should already be in the air when the party rounds the corner, ideally circling at 80 to 100 ft. up. Three Tail Spike attacks per round at 21 average damage is a real threat to a level 3 to 5 party, and the targets it picks should be the squishy with the worst AC, then the cleric, then the rogue who is trying to climb a tree to reach it. Manticores are intelligent enough (Int 7, but it speaks Common) to identify the healer and put pressure on her first. They are also smart enough to refuse melee with the paladin who is yelling for them to come down.

The fight breaks when the party finds a ranged answer. A wizard with Magic Missile or a fighter with a longbow forces the manticore to either close (bad for the manticore) or retreat (better for the manticore). Manticores are not pack animals, but they are negotiable. At half HP (34), have the manticore land on a high outcrop, shake out a tail full of spent spikes, and offer to leave if the party does not pursue. Speech is on the table. Manticores remember faces and grudges, so a party that spares one will see it again.

Describe each spike landing as a wet thunk before you call the damage. Three thunks in a round, three different PCs, and the players will start scanning the sky every encounter for the rest of the campaign.