W̷̵̱̘̗͍̦̤̣̭̞̰͓̑ͨ̂͒̾́̀͘Ḩ̶̞̬̞͎͓͚͓̎̂̍̆ͨ̎͞Ỏ̆ͩ̇͌̆͋͏̱̱ ͍͚̘͙͙̱̩̣͇̟̲͕͍͕̠'͒́ͪ̃̔̿ͬ́̾̔̂ͧ̚͟͡͏͕͍͎̱̳̻̬͙̞S̵̛̓͌̒͛͟͞ ̢̻̠̦̲̩͇̠̗͖̰̩̯̠̬͚̩ ̷̨̨̜̝͈̰̖̣͔ͮ̊ͭ͐͐ͣ͒͒̑̃͛̀͟A̴̤̩̩̤͓̙̝͔ͥ͆́͛̏͑̇ͫ̇ͧ̾͝ ̷͈̟̝͙̻̳̭͚̯͙̯̘ͬ͆̃̉̊̓̄̌̂G͌ͨ̊̅͠҉̧̱̙̳͓̼̟̀O̒̌́͌ͤͨ͆̀̂ͬͣ̿ ҉҉̵͏̥̹͙͈̝̟̭͙͈͇͙̣̺̟̪͔͇̝̼O̷ͦͦ͒̾̐ͯ̿ͤ̔ͪ͑̌̓͋̕͟͏̻̝̫͚͍̥͔͜ ̞̰̲̟D̬̙̦̩͖̫̝̞̹̱̮̭̪͔̼̳͌ͥͨͦ͝͝ ̴̶̡̜̖̮͙̥̬̌ͬ̊ͣ̎͑̓ͦ͌̐̉̽ͩͣ͊͂̚͢Ḃͬͮ̃͌̄ͬ͗ͥͦ̈̌͏̬̺̲̫͚͔̫̬ͅ ̤̳̙͓̘͇Ö̴̧̖̯̣̻̼̺̭̖́̌ͫ͌̃ͯͤ͂ͥ͡Y̗͍͕͕̱͍̟̞̮̎͗͌͐̄͂ͨ̿̃̀̚͞͞ ̥̺̼̦̥̠̙̹?̵̨̻͉̥̪̭̤̭͔̰͈̙̳͙̟̭̯̣̅ͬ̅̌̃͒͜͠?ͬͪ̃̄̌͝͏͍̠̠̀͟͟ ͓̞̺̗̣̠?͐͛ͬͪͮ̀҉̫̣̦̲̯̤̠̼̳̗͓́̕ͅͅ
The runehound, it seems, is reasonably well-known among MM3 monsters, both for being a neat low-level aberration encounter, having a cool design, and even being used in a few of the villainous competitions. also it's adorable and I love it
Anyway, it's got 5 RHD, which isn't a good start. They got some pretty nice physical stats, with 20 strength, 14 dexterity, and 17 constitution. Mental stats are slightly above animal level (5 int, 12 wis, 8 cha). Runehounds have a pretty good defensive chassis, with +4 natural armor, DR 5/silver, Fast Healing 3, and a flank immunity. The ability that provides the latter also gives an insane 500 ft. blindsight, which is great if your DM never learned what 'Darkstalker' means and good otherwise.
Offensively, runehounds have a 2d6 bite with 10 ft. reach, which is obviously great. Arguably, this ability lets it threaten a 10 ft. area even when not using its bite, like with a mouthpick weapon, but that's assuming a level of RAW-adherence I'm not sure is realistic. Runehounds also have two 'Vile Spew' attacks, which can either deal scaling acid damage or produce single-target Web effects at range. Sadly, the ability can only be used once per 1d4 turns.
Finally, there's Psychic Scent and Track, which combine to give the runehound an impressive ability to follow trails (A roll that lets a normal human track the tarrasque an hour after it passed would let the runehound track a four-day-old rat trail on a moonless night).
Is the runehound worthy of +0 LA? Barely not. If it had just one less HD it'd be a solid +0, but as it is now the lack of limbs, difficulty communicating, low BAB and lost class levels don't make up for the nice toys. -0 LA, albeit one of the better -0s, and definitely not something that should be written off right away.