Sphinxes are bosses. Probably somewhat underutilized bosses, since you can only employ the solve-the-riddle, access-the-vault trope so many times before it gets tiresome (and that number of times is generally one, if not zero), so the first challenge you have to overcome as a dungeon master, before dealing with its tactics, is figuring out a way to make a sphinx encounter feel fresh. I’ll be honest: I have no useful advice on this. If you have any, share it in the comments below.
Advanced Dungeons and Dragons had four varieties of sphinx; the number peaked in version 3.5 (the “More is always better” edition) at nine. But the fifth-edition Monster Manual includes only two: the androsphinx and the gynosphinx. The androsphinx remains the more powerful of the two, because patriarchy. (The gynosphinx, strangely, seems to have a mane, although on closer inspection, it may just be a wig.)
Androsphinxes and gynosphinxes have many features in common. Physically, they’re brute fighters; mentally, they’re champs across the board, though the masculine androsphinxes have less Intelligence and more Charisma. (If you think this makes them sound like the types who typically get promoted to management, you’re not alone.) They’re hyper-Perceptive, with 120 feet of truesight; they can’t be charmed or frightened, and they’re immune to psychic damage. At a minimum, they’re resistant to physical damage from nonmagical weapons (androsphinxes are fully immune). They can fly, at a speed greater than their normal movement. Their claw attacks are magical, and they get two per action. They have three legendary actions, which they take on other creatures’ turns: a single claw attack, teleportation and casting one spell. (Since this last costs three actions, they’ll use it only in case of dire emergency.) They have the Inscrutable feature, an ability primarily applicable to social interaction, which shields them from mind-reading. And they have a repertoire of spells they can cast at high levels.
Since they’re brutes, their default fighting mode is toe-to-toe melee, and they don’t have any compelling reason to vary it. If for some reason they decide they need to attack someone who’s not right next to them and not within flying distance, they’ll teleport at the end of that foe’s turn, when running away is no longer an option, and if they get another legendary action in between, they’ll spend it on a claw attack against that foe.
Any variety in their combat is going to emerge from the spells they cast—and the androsphinx and gynosphinx have completely different lists of spells (banishment and dispel magic being the only spells that both can cast). Most of the spells in both lists, however, are spells that a sphinx might cast as a favor or a service to a supplicant, such as legend lore, remove curse and greater restoration; only a few of the sphinxes’ spells have combat applications.
Since banishment and dispel magic appear in both lists, we can conclude that they’re important to both androsphinxes and gynosphinxes:
- A 4th-level spell, banishment lets the caster pack a target off to another plane, for up to a minute or (if sustained for the full duration) permanently. Cast using a higher-level slot, it can shoo away another target for each level higher. The gynosphinx is a level 9 spellcaster and thus can boost banishment to 5th level, removing two targets, if it knows it’s not going to be casting legend lore today, but the androsphinx is a level 12 spellcaster and can boost it as high as 6th level, removing three. Their spell save DCs are 16 and 18 respectively, and the gynosphinx’s Intelligence is high enough that it can “read” target creatures’ stats and know whether their Charisma is high enough for them to resist the spell (the spell is a safe bet for a gynosphinx if the target’s Charisma saving throw modifier is +1 or lower, for an androsphinx if it’s +3 or lower). An androsphinx, with its slightly lower Intelligence, can make very good guesses about the Charisma of a potential target but may be fooled by appearances. It knows better than to try banishment on a bard, paladin, sorcerer or warlock, but if it hasn’t had a chance to interact with a fighter, ranger or back-alley rogue—classes not known for their magnetic personalities—or if such a character has failed a social skill check to a mortifying degree, it might infer a lower Charisma than he or she actually has. In any event, the purposes of banishment are twofold: to punish the impertinent and to remove a threat, which is to say, anyone wielding a magic weapon or casting high-powered damaging spells. Any target of this spell ends up on the home plane of the deity in whose name the sphinx was originally summoned.
- Dispel magic takes care of an irksome nerf or buff. Use only if said nerf or buff is giving the sphinx actual trouble. Worth boosting with a 4th-level spell slot if needed, but not a 5th- or 6th-level slot—those are too scarce.
The gynosphinx has the following other combat-applicable spells:
- Greater invisibility can’t be used at the same time as banishment, since both require concentration, and being a brute fighter, a gynosphinx will probably opt for the latter over the former. Only if there’s no good target for banishment will a gynosphinx opt for greater invisibility instead, and only if it seems necessary somehow, for instance, if it’s taken moderate damage (40 hp or more) from ranged weapon or spell attackers.
- Darkness is highly advantageous to the gynosphinx, which has truesight, but since it requires concentration, it’s not sustainable at the same time as banishment or greater invisibility, both of which are preferable.
- Suggestion is so underpowered compared with the gynosphinx’s other abilities, I think it would only cast this spell to mess with opponents who are already failing to do any meaningful damage to it, such as by telling a ranged attacker, “I think the tension of your bow is off. You really should restring it before you try to use it again, shouldn’t you?”
- Shield is an automatic reaction in those instances when an attacker with a magic weapon rolls between 17 and 21 to hit.
The androsphinx has these combat spells:
- Flame strike is serious business, but it’s worth casting only if the androsphinx can strike at least two enemies with it at once. Good against airborne opponents. Boosting this spell increases its damage, not its area, and the sphinx would probably rather keep its 6th-level spell slot free for boosting banishment, so it will stick with casting this spell at 5th level. It also won’t cast this spell right out of the gate unless at least half of its opponents are clustered within its area of effect. This is because it will have an even better moment to use this spell later on.
- Freedom of movement is good only for freeing the androsphinx from magical restraint. (Paralysis would keep it from casting the spell at all, since it has a somatic requirement.)
- Command is only useful for provoking an opponent into incurring an opportunity attack, unless the sphinx has allies or minions at its disposal. With everything else the androsphinx can do, it just doesn’t seem worth its action cost.
- Sacred flame, because the androsphinx is a 12th-level spellcaster, does 3d8 radiant damage. Could do worse.
The androsphinx also has one last feature up its sleeve: its Roar. It gets three of these per day, and it doesn’t get to choose which effect to use: they happen in a specific order.
The First Roar frightens every non-deafened creature within 500 feet who fails his or her Wisdom saving throw, giving them disadvantage on all their attack rolls and ability checks as long as the androsphinx is within sight. It also keeps them from moving any closer to the sphinx, meaning that if it flies, leaps or teleports away from a frightened melee opponent, that opponent can’t chase it down. It takes a +4 Wisdom save mod or better to have even a 1 in 3 chance of resisting this effect. It’s a no-brainer: The androsphinx’s first action on its first turn, when it can get the most out of this feature, will always be to Roar.
The Second Roar frightens, deafens and paralyzes. This last condition is devastating: a paralyzed creature can’t take actions or reactions, can’t move, can’t speak, and automatically fails Strength and Dexterity saves (right after this Roar is the perfect moment to drop a flame strike), and the sphinx gets advantage on all attacks against the creature, with automatic critical hits against melee opponents. The time to use this action is when half or more of the androsphinx’s active opponents are no longer frightened from the First Roar.
The Third Roar does massive thunder damage and knocks opponents prone if they fail a Constitution save. The time to use this action is after the androsphinx has either followed up its Second Roar with a flame strike or decided not to.
Being divinely summoned spirits, sphinxes are not evolved creatures, so their principal motivation is duty, not self-preservation. No matter how severely injured a sphinx may be, it won’t flee, but rather will fight to the death in service to its mission.