This post is just going over a more expanded idea of how to have warframe abilities interact with each other in a way that allows for millions of different abilities to just work with each other, while maybe adding some depth to ability usage. The idea came from watching https://youtu.be/PXcF039xThQ Rahe's video about it, and while he makes some good points, I think that overall, it's not realistic to expect DE to hard code in interactions, however it is more reasonable for them to create a system where they can essentially tag all abilities with specific marker so that they can interact with other abilities based on those markers. Hard coding interactions will take a lot of effort, coding in tags to all abilities will make it a modular process of having abilities synergize with each other.
To prove how easy it is to retroactively add it to all warframes, lower on this post will be an outline for every single warframe thus far, and adding any new warframes takes a minute at most. This way, you can always count on a fireball to act as a field for any ability you ever throw at it this way. It's meant to be a simple system.
It doesn't always have to make perfect sense, and it doesn't even have to be completely balanced because having synergies is more about having fun and working together as a team for a result that is better than the sum of its parts. it may give life to old frames, it may make top end frames slightly better, but the point is that it makes playing a little bit more fun depending on what teammates you get.
And lastly: the system is made to be simple but also deep, there are very few concepts to learn, and so many applications for each concept, breaking it down to its basics, you have exploitable abilities, and abilities that exploit. Within exploitable abilities you have a two types,
Field, which are fields cast on the ground of the battle
Debuff, which are debuffs applied to the enemies
These give different effects based on what type they would grant, for instance Atlas's Path of statues would be a stop field, whenever an exploiter interacts with the field, it gains the ability to stop enemies completely for the duration of the field at the time of interaction.
Field Exploiters are as follows:
Projectiles: Carries the effect the field(s) it passes through to add more damage/effects to the projectile.
Slide: Carries along the effects of a field for a very small aoe around the player.
Warp: Takes the effect of a field and erupts with those effects in a large aoe around the warped to point.
Self Buff: Takes the effects of a field and applies a minor buff along with the normal one depending on the type. Duration based on the self buff.
Buff: Grants a minor effect based on the field it was cast from to the buffed target, duration based on the buff.
Summon: The summoned thing gains the buff of the field it was summoned in, and also creates a small explosion from the field.
Debuff exploiters is a pretty small list in comparison but that's ok as most frames have one of these abilities anyway:
Projectiles: carry along the effects of a debuff after killing an enemy (if the projectile continues on)
Explosive: When you kill an enemy with a debuff that debuff is spread in a small aoe
Reward: Grants a bonus buff upon killing an enemy, based on the debuff type.
In a very specific interaction of how it should work lets go with even a single warframe interacting with itself (which is debatable, it could cause certain frames to become a lot more powerful), atlas's landslide interacting with a path of statues and petrify/ore gaze.
He slides through the path of statues, gaining a stop for all enemies he slides near or into, then when he hits the enemy, who was already petrified, the enemy then explodes with more stop in a small aoe, while also rewarding atlas with Sure Footed for a few seconds after because the enemy was Stopped and exploited with Reward. While atlas doesn't need sure footed, it can still be useful to other frames and is meant to be a small bonus for playing in a synergistic way.
In a 4 player team, this could get really ridiculous, but I think that's a good thing.
if you want to make it a little more balanced you could make it so that you can't interact with your own fields/debuffs, only allies can.
Edit: The forum really doesn't like how nested everything is, you'll have to scroll down to get to the warframes, the first one is Ash, it goes in alphabetical order.