Sphinxes already made their 4e debut on the Monster Manual, and the MM2 gives us an additional variant.
The Lore of the Sphinx Mystery
All sphinxes have a common origin as sacred guardian beasts, as described in the Monster Manual entry, but not all of them are exactly alike. This stat block represents an individual with preferences and abilities different from those of the typical MM1 sphinx.
All sphinxes have the ability to propose challenges that help separate intruders from visitors who have a right to be at the places they guard. Riddles are a classic but are far from the only option, and the MM1 entry made some effort to stress that part. Here, though, we go the other way.
The Sphinx Mystery is an individual who’s way into riddles. She doesn’t just use them as her basic authentication scheme: she also uses them as weapons in the middle of an actual fight. She likes riddle games so much that she might just choose to keep playing rather than fighting with lethal intent, if her opponents can keep the game fun for her.
Intruders who can’t answer those riddles are in real trouble, though, because they do real damage and are as sticky as warlock curses.
The Sphinx Mystery is a Level 19 Brute with 224 HP. Despite being a regular, she still has an action point. This might be an editorial error, but it’s fun so I’d keep it. She also has low-light vision, and moves at ground and air speeds of 6.
Most of her attacks are part of the standard lion beast arsenal. The likely fight-opener is a a Terrifying Roar (encounter) that targets Fortitude, deals thunder damage, pushes 5 squares, and knocks prone. Her basic attack are Ancient Claws that do heavy damage, and she can also use a Bite of Ages that deals light damage, knocks prone, and immobilizes with the weight of history (save ends).
As a minor action, the Mystery can use Riddle Me This (Ranged 10). This is an at-will ability that represents the sphinx compelling someone to solve a riddle. This “hits” automatically, and dazes the target until the riddle is answered or until the encounter ends. Answering the riddle requires spending a minor action and succeeding at a DC 25 History check. Anyone can attempt the test on their turn, not just the affected PC.
If the targetted PC doesn’t attempt to solve the riddle on their turn, they take 2d8 psychic damage at the end of that turn. They also take this damage if someone else answers the riddle for them. This damage is light, but about in line with the amount of “traditional” ongoing damage an effect at this level would cause.
Note that the target will be dazed, which means that if they attempt to answer the riddle, that’s the only thing they can do on their turn. So it might be better to let an unaffected buddy answer it and eat a single instance of that psychic damage.
The Mystery’s last attack is the amusingly named Corrective Maul, which is a claw attack that does even more damage and recharges whenever anyone fails to answer one of her riddles.
Sample Encounters and Final Impressions
The riddle mechanic is awesome! It makes the sphinx very controllery despite her being a Brute. Since the riddle is ranged, you’ll want to delay her entry into melee combat a bit until she can apply it to every PC. As a regular monster, the sphinx will always be found alongside a few buddies, so they can help with that.
The sample encounter is level 16: 2 nothic cacklers, 2 savage minotaurs, and a sphinx mystery. This is either an evil sphinx running with other assorted marauders, or a more traditional guardian who has managed to recruit several would-be intruders to her service through riddles and bets.