Chrono Trigger-style Dual Techs in 5e

Chrono Trigger is one of the greatest games ever made. Everything from the complex plot to the incredible soundtrack to the lovable characters and their interactions with each other has an element of polished quality to it that is hard to find anywhere else. Its storyline in particular, with its themes of time travel and preventing the end of the world, is very inspiring for a D&D campaign.

There's one mechanic Chrono Trigger has in particular that I'm amazed isn't more widely used in other games: Dual Techs and Triple Techs. Each character has an individual list of techniques, or Techs, that they can use on their turn. The swordsman Crono, for instance, has a tech called Cyclone, where he spins around with his sword, hitting a group of enemies. The princess/water mage, Marle, has a tech that heals a singular ally. The characters have the option to use their turns at the same time and combine their abilities, in which Marle channels healing energy onto Crono's spinning blade, causing it to heal all allies. The game even has Triple Techs, where three characters use their abilities in tandem, causing extremely powerful and versatile effects.

In a game like D&D where group storytelling is heavily focused on, Dual Techs would be an amazing way to promote teamwork, invent creative combinations of abilities, and otherwise enhance the game. In order to make techs that are balanced and worth using, I think that Dual Techs should follow these rules:

1. Using a tech should be more effective than the sum of their effects
2. Using a tech should use both characters' actions and a resource of some kind.

Effective Techs

From what I can tell by looking into Chrono Trigger's tech damage formulas, the effects of Dual Techs compared to using each individual tech separately fall into these categories:

• It deals anywhere from 0–50% extra damage
• It changes the damage type, sometimes to something that more enemies in the game are weak to
• It adds status effects or other bonus effects to the result
• It alters the scope of the attack, for example, changing a line attack to a circle, or a circle to all enemies in the entire encounter.

Percentages (other than 50% and 200%) kind of go against 5e's rules of simplicity, and making up a Dual Tech on the fly should be as simply as possible while still being balanced. Hence, instead of requiring the players to calculate if the combined damage total is 1.3x or 1.5x or whatever, I'd say just go with how cantrips' damage dice numbers scale and add that to the total. For example, if some 3rd-level PCs did a Dual Tech and the total damage was 5d10, add an extra 1d10 to the total. At 17th level, you would add an additional 4d10. That way, regardless of the power of the individual attacks, you're getting an additional damaging cantrip cast in there too, which would make the damage more significant.

Damage amount isn't the only thing a Dual Tech should be focused on, though. The real fun in Chrono Trigger is how the two techs mix together and how the resulting Dual Tech is an epic mix of the two that adds tactical advantages as well. Obviously, the first place you should look for inspiration is the two separate abilities, but here are some basic ideas for making a Dual Tech stand out:

• If an attack roll is involved, the attack is made with advantage.
• Add a condition, such as blinded, deafened, frightened, or prone, or have them lose their reactions or halve their movement.
• Change the combined damage type to Force or Radiant, which most enemies in the game are not resistant to. 
• Change a normal targeted attack to a line attack, a line effect to a cone, or a cone to a sphere.
• Increase the effect's range or radius.
• Allow both players to maintain concentration on the spell. As long as at least one of the players is concentrating, the spell persists, even if one of them stops.
• Make a single-target attack's effect extend to all enemies within a radius instead. This should generally require a saving throw and reduce the damage since it's being split up among multiple targets. An easy way would be to either halve the damage or lower the damage die size by 1 or 2 (e.g., a d10 down to a d8 or a d6).

And if the players crit on an attack, maybe add something extra still. If these joint attacks are limited, each one should be memorable, and what's more memorable than a critical hit?

Most of the fun of allowing a Dual Tech is letting the players decide what it does, but these guidelines should at least help you establish boundaries. Finding a balance and a synergy between the two separate abilities will make it stand out without breaking an encounter. 

Resource Cost

While holding your action to use your attack until your ally's turn is technically more costly (at least in terms of risk) than simply acting separately, if a Dual Tech is designed with synergy, something limited should be required in order to pull them off.

In Chrono Trigger, the only cost of using a Dual Tech is the TP cost of each individual tech, plus using both players' turns at the same time. Sacrificing both turns seems like a elegant and simple way to harmonize the two players' attacks and make them feel coordinated. In addition, if a Dual Tech is to be as powerful as it feels, it should also cost some other type of resource, depending on the class:

• Artificer. Spell slots
• Barbarian. Uses of rage
• Bard. Uses of Bardic Inspiration, or spell slots
• Cleric. Uses of Channel Divinity, or spell slots
• Druid. Uses of Wild Shape, or spell slots
• Fighter. Uses of Second Wind, or uses of Action Surge
• Monk. Ki points
• Paladin. Uses of Channel Divinity, or spell slots
• Ranger. Spell slots
• Rogue. Not being able to use Sneak Attack or Cunning Action on the following turn
• Sorcerer. Sorcery Points, or spell slots
• Warlock. Mystic Arcanums, or spell slots
• Wizard. Spell slots

Another simple way to add a cost, especially for martial classes, is to just give them a level of exhaustion that goes away after the combat ends, or after a short rest. And if an effect lasts an extended period of time, perhaps both of the players have to maintain concentration on it, and the effect ends if either one of them breaks it.

Although this adds a balance to using Dual Techs so that they aren't just used at will, some DMs (me included) may want to ensure that Dual Techs stay fun, significant, and impactful, and don't get worn out by too much use. One way to ensure this is to also require one use (per Dual Tech) of Heroic Inspiration to do it. This adds an additional incentive to earn Heroic Inspiration in the game and makes it feel extra heroic, especially if one of the player characters not even included in the Dual Tech is allowed to sacrifice their own Heroic Inspiration to help allow it to happen. It encourages even more teamwork, which is exactly what this mechanic is all about.

Basic Rule Formula

Here's how I would describe the requirements for a Dual Tech to players:

The first player must ready an action to set up the Dual Tech. The second player must use their action to execute the Dual Tech, which then activates as long as the players are within 30 feet of each other. If an effect lasts or activates at the start or end of "a player's" next turn, the second player's turn is the one used.

Example Dual Techs

Below are some examples of Dual Techs that I would allow mechanically in my own games. I would encourage the players to do the describing of how the actual attack happens, since seeing the effects come together is one of the most rewarding aspects of Dual Techs in Chrono Trigger. Each Dual Tech is given as if it were at the lowest level possible for the spells and abilities used.

• Smite of the Stars. A cleric casts guiding bolt on her ally fighter's hammer. The paladin expends a 1st-level spell slot and makes an attack roll with advantage against a target. On a hit, the target takes an additional 2d8 radiant damage, and regardless of a hit or miss, a burst of light erupts from the hammer's blow. All enemies within 10 feet of the paladin take 2d6 radiant damage and the next attack against each target before the end of the player's next turn have advantage.
• Thunder Slash. A bard casts shatter on his ally wizard bladesinger's blade. As the roar crescendoes, he expends a 1st-level spell slot and casts booming blade, which causes an eruption of thunder damage in a 30-foot radius. All enemies within that area must make a Constitution saving throw, taking 4d8 thunder damage on a failed save, and all of them are sheathed in booming energy until the start of the latter player's next turn. If any of the targets willingly moves 5 feet or more before then, it takes 2d8 thunder damage. On a successful save, a target takes half damage and the booming energy does not have an effect.
• Hex Arrow. A warlock casts hex on his ally ranger's arrow, which wreathes it in black smoke. The ranger takes a level of exhaustion and shoots the arrow with advantage 300 feet at a target creature. On a hit, the creature takes an additional 2d6 necrotic damage and is hexed as per the spell.
• Combined Spell. A wizard and a sorcerer each gain a level of exhaustion and expend a 2nd-level spell slot. They then both cast a 4th-level spell from either of their spell lists.
• Elemental Augmentation. A druid casts cone of cold as her ally monk attacks with a Flurry of Blows. For the next minute while the druid is concentrating, every unarmed strike the monk makes deals an additional 2d8 cold damage, and ranged attacks against the monk are made with disadvantage as a howling wind blows projectiles off course.

Dual Techs don't all have to be combat-focused like these ones, but that's what their appeal is in Chrono Trigger. Combining spells and abilities outside of combat in interesting ways could be a great way for players to solve puzzles together, but I would focus more on the situational epicness of Dual Techs, which functions better in combat situations.  

Triple Techs?

Chrono Trigger doesn't just have Dual Techs, it has Triple Techs where all three members of the party work together to create truly epic feats. The rules for such an ability would be similar to that of a Dual Tech, except that the first two players would have to ready their action and the third player would activate it. The complexity of a Triple Tech is beyond the scope of this article and probably more than I would be able to handle as a DM, but I would make such acts extremely powerful but come at a very restrictive cost, perhaps requiring all three players to expend Heroic Inspiration in addition to each taking a level or two of exhaustion. These types of combined efforts would make an amazing end to a final boss fight, but I wouldn't want players to use them in every encounter.