When the Plains of Eidolon came out, something else was added as well, slipped in for us to sort of consider later, and offered mainly as bounty rewards. These were the three set mods, the Augur, Vigilante and Gladiator set mods. The concept behind these mods is simple: you use one of these mods, you get a small bonus. The more mods in the set that you use, the stronger the bonus will be. The Augur mod set gives you shields whenever you use energy, the Gladiator set gives you 15% melee critical chance, which stacks with your melee combo (like the mod Blood Rush but weaker) and the Vigilante set has the unique ability of giving you a chance to upgrade your critical damage – turning yellow crits into orange crits and orange crits into red ones.
These ended up being soemwhat popular, so more set mods were soon added. The Hunter set mods were released with the first appearance of Plague Star and the Ghouls. Technically, the three Umbral and Sacrifical mods are also set mods, since equipping more than one gives you bigger bonuses – they increase the stats of the mods themselves rather than boosting a secondary stat.
When Fortuna came out, we got more set mods – the Tek mod set aimed at Kavats, the Synth mod set aimed at Sentinels and MOAs, and the Mecha mod set for Kubrows. A further set of mods, the Strain mod set, came out when Profit Taker was released. Then we got even more mod sets, the Aero, Proton and Mote mod sets, which all came alongside Wisp and the Jovian Concord update.
Each mod set has its own unique buff, but some of them are more useful than others. The Synth mod allows you to reload ammo while holstered which benefits your Warframe greatly, while the Mote set gives you knockdown reduction only when you’re airborne, which… isn’t that useful in the grand scheme of things. The Gladiator mod set is genuinely useful if you use melee a lot, but requires a lot of work to be as powerful as just sticking one mod on your melee weapon (although the effect does stack with Blood Rush). Some seem useful on paper, like Aero’s ability to put up to 5 enemies to sleep if you damage them while airborne, but most enemies aren’t really alive long enough for that to be worth anything. The Strain set doesn’t seem to really fit in anywhere since all the mods are focused on creating little Helminth maggots rather than having stats that are useful for you and your Helminth Charger.
But there’s a big problem with mod sets. No one ever uses all of them. The mods are either inferior versions of other mods, there’s nowhere in your loadout to use them or the mods just aren’t useful in general. Sometimes the problem is all three.
For example, the Augur set actually contains some pretty good mods, but all of these are inferior to existing mods. Augur Message is a weaker Continuity (ability duration), Augur Secrets is a weaker Intensify (power strength) and Augur Pact is a weaker Hornet Strike (pistol damage). But some of the mods in the set, namely Augur Seeker (status duration for pistols) and Augur Accord (shield capacity) are just not worth using at all.
And trying to use all the mods in a set causes headaches more than anything else – while it is doable, you end up having to remove essential mods in order to fit all these mods on, or have to use specific loadouts, weapons and companions. You can easily use the whole Aero set, but this means you HAVE to use a sniper rifle. It’s often better off just to use some of the mods and not get the complete bonus, simply because there are far better mods you should be using.
Some of these mods though do go nicely when used alongside their normal variants. Vigilante Armaments (multishot for rifles and shotguns) can be used alongside Split Chamber/Hell’s Chamber (the normal multishot mods) without any downside, and Augur Message can be used alongside Continuity for even more ability duration without sacrificing other stats.
There is an exception – the Umbral mod set is regularly used because that’s given to you for free for completing the Sacrifice and any way to increase Power Strength is always a big thing. I don’t know a single person who will actually uses maxed out other mod sets though. You also can’t use Umbral/Sacrifical mods alongside their normal variants, because they are considered the same mod.
The idea behind set mods is really awesome, but a lot of the time, it’s only ever worth using just one or two of any mods in a set, simply because they’re the most useful. Still, I do look forward to new mod sets, because there’s always some sort of niche trick to them…