How to Mod

With these tips, tricks, & hints you too can mod with the best of them.

Capacity

Every mod has a drain cost. Your item has a capacity budget. Rank a mod up and the drain usually goes up with it. Go over budget and the build is illegal.

At max rank, capacity is usually around 30 before a potato (some items go higher). Unranked or freshly Formad gear starts lower, so early builds feel cramped.
A Catalyst (weapons) or Reactor (warframes and similar) doubles capacity. This is the first real unlock for serious builds.
Mastery Rank raises the starting capacity floor on low-rank or freshly Formad gear. It does not raise the max on a finished rank-30 item. Potatoes still matter.
On warframes, a matching-polarity Aura can add capacity instead of spending it. Aura choice is part of your budget.

Tip

Potato the gear you actually play. On everything else, use low-drain mods until you know you will keep it.

Polarity & Forma

Polarities are the symbols on slots and mods. Match a mod to its polarity and the drain is cut in half (rounded up). Mismatch costs about 25% more (also rounded). An empty polarity is neutral: no bonus, no penalty.

Formasets or changes a slot's polarity. It also resets the item's rank, so plan before you spend it.
Polarize the slots under your heaviest mods first (Primed, Umbral, high-rank Galvanized, etc.), not under a tiny utility mod.
Umbra mods want Umbra slots. When in doubt, match whatever drains the most.

Common mistake

Forma-ing every slot to random polarities "for the future." You will fight your own grid every time the build changes. Forma for a concrete plan.

Don't double the same bonus

Not every "+damage" works the same way. A lot of bonuses add into the same pool. Two Serration-style effects stack with each other, so the second one is a smaller relative gain for a full slot.

Other bonuses hit different parts of the formula: multishot, crit chance, crit damage, faction mods, and some ability buffs. Those often multiply your whole package instead of fighting for the same +% bucket.

Do: one strong base-damage source, then diversify into multishot, crit, elements, faction, or conditionals.
Don't:equip two mods that both just say "damage" without checking if they share a pool. Frame buffs and weapon mods can share pools too.

Tip

In FrameHub, swap one mod at a time and watch DPS or ability stats. If the number barely moves, you found a double additive.

Elemental combos

Heat, Cold, Electricity, and Toxin combine into combos like Viral, Corrosive, Magnetic, Radiation, Blast, and Gas. Combination follows mod placement order: left to right, top row then bottom. Decide the combo you want first, then place mods so you get it. Full combo table is in Elements.

Innate elements on the weapon count and combine last, after your elemental mods. Placement still matters. If the combo looks wrong, check the builder.
Common gun pattern: Viral + Heat. Corrosive for armored targets. Pick for the mission, not for "more colors."
Plan 1-2 elemental mods on purpose. Random extras often make the wrong combo and dilute the procs you care about.

Common mistake

Adding every elemental mod for more status types. You usually weaken the setup instead of improving it.

Can't equip both?

A lot of mods are exclusive with their upgraded cousins. You cannot run Point Blank and Primed Point Blank together, or Continuity and Primed Continuity. Umbral sets, Archon variants, and some Galvanized lines have the same kind of rule. If the game (or FrameHub) blocks a second mod, it is usually exclusivity, not a bug.

Pick the stronger legal option and free the other slot for something that multiplies a different part of the build.

Next: Elements Weapons