Blink Dog

A blink dog on the party's side is a scouting and skirmish tool, not a tank. It has 22 HP, AC 13, and a single Bite at +5 for 5 damage, which is a CR 1/4 statline you should not pretend is anything else. The value is the Teleport bonus action: 40 feet to any unoccupied space the dog can see, on a recharge of 4 to 6. Run the dog like a Misty Step on legs.

Blink dogs are Lawful Good Fey with a small language of their own and an understanding of Elvish and Sylvan, so the druid or the elven ranger can usually translate. Use that channel for one piece of useful intel per scene and one warning per combat. The dog will not fight evil for evil's sake; it fights gnolls because it is a blink dog and that is what blink dogs do, and it will leave if the party asks it to do something it considers wrong. Make the alignment a soft constraint the players notice, not a leash.

In combat, lead with Teleport into a flanking position behind a caster or archer, then Bite. The 40 ft. walking speed and Pack Tactics-shaped logic of "show up next to the squishy" makes the dog a fine threat for a single round of an enemy back line. After that, Teleport the dog out, because it cannot survive a focused turn from anything CR 2 or higher. Stealth +5 plus Teleport recharge means a smart blink dog never ends a turn within an enemy's reach if it can help it.

Out of combat, the dog scouts, carries small messages, and refuses to enter cursed ground. Treat it as an NPC the players are responsible for, not a pet they own.

Give the dog a name only the druid knows how to pronounce correctly. The mispronunciations from the rest of the party become a running joke, and the dog visibly winces every time.

A blink dog as adversary needs a setup. Pack-of-blink-dogs is the standard answer: the party has wandered into a Feywild glade where a pack mistakes them for poachers, or a corrupted blink dog has been Geased into service by a hag and is hunting a specific PC. Lean on the Lawful Good alignment for tragedy. These are not evil dogs; they are wrong about the party, and the party will feel bad killing them.

Run a pack of three to five for a level 2 to 4 party. Open with simultaneous Teleports from cover into a circle around the squishiest target. Each dog Bites and then, on its next turn, Teleports back out before melee can land. The DM trick is to track each dog's recharge separately. A pack where two are mid-recharge is in trouble; a pack where all five just teleported in fresh is brutal.

Blink dogs do not fight to the death over a misunderstanding. The first dog to drop is a clear "we have made a mistake" signal, and the rest withdraw via Teleport on their next turn. If the party can land a Speak with Animals, Tongues, or any Sylvan speaker, the fight ends in conversation and a possible apology scene.

Telegraph the pack with one harmless blink, far away, the round before they engage. Players who see a teleporting dog at a treeline will brace for it.