The four elder elementals in Mordenkainen’s Tome of Foes have a lot in common. To me, the most striking commonality is that they’re exceptional, if not extraordinary, in every single ability score but one: Intelligence. Each of them has Intelligence 2, indicating bare-minimum sentience.
Once again, we see the combination of low Intelligence and high Wisdom, only this time it’s dialed up to an extreme. What does it mean to have Intelligence 2 and Wisdom 18 or 21? It means intuition without thinking, awareness without adaptability, judgment without reason. It means a creature that acts according to its nature and can’t be compelled to do otherwise. It means a creature that senses the degree of threat that a party of player characters poses but can’t really distinguish any one of those PCs from any other.
These are the other traits shared by all elder elementals:
- At least two physical ability scores that are higher than all their mental ability scores.
- Proficiency in Wisdom and Charisma saving throws, making them extremely difficult to manipulate or to banish.
- Resistance to physical damage from nonmagical attacks.
- Immunity to poison damage, exhaustion, paralysis, petrifaction, and being poisoned or stunned.
- Darkvision out to a radius of 60 feet, which in this case I interpret to indicate not a preference for fighting in dim light or darkness but an indifference to lighting conditions in general.
- A lack of language. Elder elementals aren’t here to chat.
- Legendary Resistance, which they’ll use primarily to avoid debilitating conditions and only secondarily to avoid damage.
- The Siege Monster feature, which means they’ll destroy your cover before they destroy you.
- A Multiattack comprising two different attack actions, one attack with each.
- A selection of legendary actions that includes one turn’s worth of additional movement.
- Neutral alignment. The default attitude of an elder elemental toward other creatures is indifference. It’s not going to attack—intentionally—unless it’s provoked. But who knows who or what might provoke it?
What’s going to distinguish one elder elemental from another are the features that are unique to each one. Differences in damage resistances, damage immunities and condition immunities aren’t going to count for a lot, because these are passive features and because the elder elementals’ Intelligence scores are so low, they’re not going to fixate on, say, an opponent who’s dealing acid damage vs. one who isn’t. At most, they’ll help determine when an elder elemental chooses to use Legendary Resistance or not to use it.
The ability contour of the leviathan, the elder elemental of water, peaks in Strength and Constitution, making it a melee-oriented brute. If a leviathan is provoked into fighting, it charges its enemies and tries to stay on top of them—literally, since its Water Form feature allows it to share space with hostiles—after first smashing any cover they have or vessels they’re using to stay afloat.
The leviathan’s Tidal Wave action is hugely powerful, with effects that persist for as many as five subsequent rounds. Given this, it seems like a waste for it not to use Tidal Wave on its very first turn—and, in fact, the 66 points of expected damage it does to each creature affected by it, in aggregate, beggars the total 44 points of damage it does if both attacks that constitute its Multiattack hit.
However, Tidal Wave recharges only on a roll of 6. In other circumstances, we might expect a monster to save such an ability until it knows it needs to use it. In the case of the leviathan, this action might be “unlocked” by the infliction of cold damage, since its Partial Freeze feature renders it vulnerable to large amounts of this type of damage.
But I’m going to go with a different interpretation: Elder elementals are all creatures of impulse and temperament. They don’t care about you unless and until they’re provoked, at which point they lash out. So if your PCs have already poked the leviathan, I don’t see any reason why it will feel a need to hold back. Tidal Wave right out of the gate it is. The leviathan’s Siege Monster feature includes a specific exception that includes objects and structures among the targets affected by Tidal Wave, so apply that bludgeoning damage to the PCs’ ships, boats and coastal fortresses—and remember to double it.
On subsequent rounds, if Tidal Wave recharges, the leviathan gets on top of its foes and uses it again. If not, it indiscriminately Multiattacks nearby enemies.
What moves a leviathan to spend two legendary actions on an extra slam attack? Nothing but caprice. If the leviathan’s last enemy has just moved out of its 20-foot reach, it will use its Move legendary action on the same turn to pursue. Otherwise, at the end of each PC’s turn, just roll a d4 or d6 (depending on how many opponents the leviathan has), and if you roll a 1, have it Slam. (No need to roll if the leviathan doesn’t have two legendary actions available to it.)
The leviathan uses its Legendary Resistance whenever it fails a saving throw against being blinded, taking any amount of cold damage, or taking moderate damage (99 points or more) of any other type from any single source.
The phoenix’s ability contour peaks in Dexterity and Constitution, so it’s going to take a more skirmishy approach, which is facilitated by its Flyby feature. Its default behavior is to stay airborne about 60 feet from its target, swoop in to Multiattack (from the target’s own space, thanks to Fire Form), then use the rest of its movement to fly back out of reach. Thanks to Flyby, it doesn’t incur opportunity attacks.
Clever PCs, when they see that they don’t get opportunity attacks when the phoenix flies out of their reach, will Ready Attack actions that trigger when the phoenix flies into their reach—or they may have the Sentinel feat and get a reaction attack in addition to their turn actions. Phoenix don’t care. In addition to its Multiattack, its Fire Form deals 1d10 fire damage automatically just from entering the target’s space, and if the target strikes it with a melee attack, he or she gets dealt another 1d10 fire damage. Fire Form also ignites flammable objects in the phoenix’s environment, which includes wooden structures—and thanks to Siege Monster, the damage dealt to such structures is doubled. (Like other elder elementals, the phoenix destroys cover first, then turns its attention to soft targets.)
Unlike the leviathan, which uses its legendary Move action to chase its foes, the phoenix uses its legendary Move action to stay out of melee reach. It uses Peck and Swoop only against inanimate structures that can’t fight back and against living targets who’ve already used their actions and won’t get to attack again before the phoenix’s own turn, and only if doing so doesn’t bring it within movement-plus-melee reach of another opponent who can attack before the phoenix does. It uses Peck to continue attacking a target that’s already within its reach, Swoop if the target is between 20 and 120 feet away.
The phoenix uses its Legendary Resistance whenever it fails a saving throw against being blinded or taking moderate damage (53 points or more) of any type from any single source.
The tempest has only one ability contour peak, in Dexterity. It would be happy to attack from range if it could, but it doesn’t have a ranged weapon or spell attack, so it relies on high-damage shock attacks instead. Like the phoenix, it has Flyby and uses this feature to fly out of reach after attacking without incurring opportunity attacks. When it Multiattacks, it always directs both of its attacks against the same target in order to maximize its damage.
Lightning Storm, like the leviathan’s Tidal Wave, is a recharge ability that the tempest can use, on average, only one turn out of six. Unlike Tidal Wave, it doesn’t damage structures or objects, only creatures. Thus, the tempest’s first priority is to demolish any structure that’s sheltering a ranged attacker from the winds of its Living Storm. Its second priority is to fly just close enough to its opponents that it’s within 120 feet of all of them, then let loose a Lightning Storm. Since targets that fail their saves by 5 or more are stunned, the tempest exploits this condition to Multiattack one of these targets with advantage on the following turn—that’s its third priority. However, if Lightning Storm recharges immediately, it uses that action again. Its fourth priority is to demolish other cover protecting its opponents, and its fifth priority is to thunder-buffet non-stunned targets.
Like the phoenix, the tempest uses its legendary Move action to stay out of its enemies’ reach. Lightning Strike, like Lightning Storm, doesn’t affect objects or structures, so like the leviathan and its legendary Slam action, the tempest uses Lightning Strike out of spite and whimsy; roll a die to see whether it bothers. Screaming Gale is highly situational and expensive in its legendary action cost; the tempest uses this legendary action if and only if all its opponents are clustered within a 20-foot horizontal band in front of it.
The tempest uses its Legendary Resistance whenever it fails a saving throw against being blinded or taking moderate damage (80 points or more) of any type from any source.
The zaratan, like the leviathan, is a brute, moving directly to engage in melee when it attacks—but not necessarily at full speed. If its opponents are protected by a structure that gives them cover, it first approaches to within 120 feet of it, then advances just 10 feet at a time, using Earth-Shaking Movement as a bonus action to inflict damage to that structure each turn, then using its Spit Rock action to inflict further damage to that structure—doubled, thanks to Siege Monster. It does this until the structure is destroyed, then resumes advancing at full speed.
Spew Debris is a recharge ability with a more typical recharge rate, but it doesn’t affect objects or structures, so the zaratan will refrain from using it until all its targets’ cover is destroyed. Once this is the case, it won’t hesitate to use this ability whenever it’s available. Otherwise, it defaults to its Multiattack, which it uses indiscriminately against opponents within its melee reach—including against any remaining cover.
The zaratan is immune to fewer conditions than its fellow elder elementals; it’s also the only one with a damage vulnerability, thunder. Thus, it uses its Legendary Resistance whenever it fails a saving throw against being blinded, knocked prone or restrained; taking any amount of thunder damage; or taking moderate damage (93 points or more) of any other type from any single source.
The zaratan also reacts to thunder damage by using its legendary Retract action, followed by Revitalize and Emerge at their next earliest opportunities. This takes a while, because these stunts cost two legendary actions each, which means the zaratan has to take a turn in between Retract and Revitalize and another between Revitalize and Emerge.
While the zaratan is Retracted, it’s restrained—but a restrained creature can still take actions! It just can’t go anywhere, and it attacks with disadvantage. It can stick its face out and Spew Debris, though, if that ability is available to it. As for the third legendary action it’s not spending on Retract or Revitalize, that one’s probably just wasted: Move won’t get it anywhere while it’s restrained, and it won’t bother to Stomp when it would have disadvantage on the attack. When it finally Emerges and spits a rock, it will aim it directly at whatever jerk dealt thunder damage to it.
Any other time, the zaratan’s default legendary action is Stomp, unless the last of those opponents within its reach moves away, in which case it uses Move to give chase. The only time it uses its legendary Spit action is while it’s busy demolishing structures and other cover; once those are all gone, it doesn’t use this legendary action anymore.
No elder elemental ever retreats from battle, however much damage it takes. Elder elementals are slaves to their temperaments, and they’re not native to the material plane anyway, so they have no particular attachment to it. For them, being destroyed is ultimately a kind of freedom.
Next: elemental myrmidons.