Bugbear Stalker

A bugbear stalker working with the party is a hire, a hostage situation reversed, or a rare defector from a warband the party broke last session. Bugbear stalkers speak Common and Goblin, so unlike most bugbears in the bestiary this one can actually negotiate, and that's the whole reason to bring it in. The party gets a chain-shirted Stealth +6 scout who will absolutely take a job for the right pile of coin and absolutely vanish if a better one walks past.

In play, position the stalker as the silent half of a two-step. Send it ahead with Stealth to find the camp, then have it Quick Grapple the sentry on a DC 13 Dex save while the party closes the gap. Abduct lets it move a grappled creature without paying extra movement, so the standard sequence is: grab the lone watch, drag them out of earshot, hand them to the party for questioning. That single trick is worth more than the morningstar damage.

Combat-wise, the stalker is a mid-tier melee bruiser. Two attacks at +5 with the Morningstar (12 average per hit, advantage on a grappled target) put it in the same damage band as a fighter of comparable level. With 65 HP and AC 15, it can hold one flank for the party's casters but not two. Treat it like a low-level NPC fighter the party is renting, not a member of the team.

The thing that makes a bugbear stalker memorable as an ally is the moment its loyalty cracks. Have the party walk past a crate of unguarded silver. Roll a Wisdom save in front of them. Whether it makes the save or fails it is the more interesting question.

A bugbear stalker is the goblin warband's kidnapper. It does not fight a stand-up fight, it picks the sentry off the watch, the cleric off the back rank, the cook off the supply line, and drags them into the woods to be questioned, ransomed, or worse. Place one in any goblinoid encounter where the party should feel the threat is targeted and personal, not random.

Open with Stealth +6 and Darkvision. The stalker should be in position before initiative is rolled, ideally with a partial-cover ambush angle on the most isolated PC. Round one is Quick Grapple as a Bonus Action against the chosen target (DC 13 Dex save), then a Morningstar swing with advantage from the grapple, averaging 12 damage on a hit. Round two is Abduct, which lets it move 30 ft. while dragging the grappled PC without spending extra movement. Combine that with the 10 ft. reach on its weapons and the stalker can keep a target out of range of the rest of the party while still attacking.

Target priority is the squishy who can't escape the grapple on their own. Wizard, sorcerer, low-Strength rogue. Avoid the paladin. If the party rallies and the stalker drops below ~20 HP, it ditches the grapple, throws javelins as it backs off (range 30/120), and disappears into terrain. Bugbear stalkers report back to a boss; they do not die alone in the woods to make the players' job easier.

If the party doesn't rescue the abducted PC inside two rounds of pursuit, frame the recovery as the next scene rather than a TPK. The abducted character wakes up tied to a chair somewhere new. That's a better story than "the rogue died because of a grapple."