Hideous Resistance

Idk, maybe to counter fire eximus

It also can generate energy with its augment if you have grouping capabilities.

It also act as primed sure footed for ability duration.

Self stagger will also consume charges, even if Prime Sure Footed is equipped. Therefore you can cause yourself to lose all of your own stacks by accident if you use a weapon like the Kuva Zarr and fire at an enemy too close to you.

I noticed when using this that it prevents knockback/knockdown from various sources. The most beneficial being self inflicted when using any blast weapons such as Kuva Ogris. The Grineer bomber/napalm ability that does the aoe fire will bounce you but it does not knock you down. Once I noticed this and began firing rockets from Envoy into the floor and wall and I never budged. I cannot think of any mod or ability that would prevent these knockdowns as I messed around with it over several missions. Even with spellbind active I will be knocked back/down so I never considered knockdown as a status effect but perhaps I am mistaken. The Charges are also affected by one of the stats but I cannot remember which one (possibly strength). I was holding 22 charges on Nekros and with the exception of acolytes who strip your buffs, those charges lasted quite a long time. I found it to be much more beneficial than Spellbind unless you are using spellbind to buff your group.

"I cannot think of any mod or ability that would prevent these knockdowns"

-Inaros' augmented Scarab Armor

-Atlas just standing there

-Gauss' Kinetic Plating

-Nezha's Fire Walker (Subsumable, but only the lingering flames provide immunity = only useful when you stay in one area for some time)

-Nezha's Warding Halo

-Nidus' Parasitic Link

-Rhino's Iron Skin

-Frost's augmented 4

-Revenant's Mesmer Skin

-Oberon's Hallowed Ground

-Titania's Spellbind (Subsumable) (yes, it provides knockback/down immunity. Did you make sure to hold the cast?)

-Trinity's Link

-Yareli's Merulina

-Ember's augmented 3

-Nekros's augmented 4

-Ivara's augmented Quiver thing

-Hydroid's Tidal Impunity

-Valkyr's Hysteria (if the melee is out, so not very useful)

-Nyx's Assimilate

And for everyone else:

-Primed Sure Footed (Exilus)

-various other knockdown protection mods with less percentage)

Effigy can double credits, so it is not wise to replace that ability. His first ability, on the other hand, is something that you can happily remove.

It doesn't need ability duration.

I've got primed sure footed BTW

Likely each rocket from multishot doing a separate stagger, each using up a charge.

I'm using a ogris and same result, at leas 2 charges are consumed each time I shoot at my feets

Not only does it feel worse. since at 300+ u only have 30 ish stacks and all the AoE weapons will take off 3-10 stacks depending on the multishot of the weapon.

Which just feels much worse in the long run.

Not having it completely rely on duration is of some benefit but over the stack cost is too high for most warframes to use in a normal build scenario

As @Cynical Millennial pointed out, this ability functions on low duration frames where Spellbind would not. Baruuk comes to mind, since he's commonly run at low duration and high strength. EV Trinity could also benefit, as low duration pretty much craters Link's effectiveness to negate statuses. A low duration Silence Banshee could feasibly use this if they wanted. None of those would work well with Spellbind.

So the core mechanic I think is sound, and it gives us another option besides Primed Sure Footed, which is expensive in more way than one.

Now, as to the actual stack numbers, I think there's a pretty good argument that the base stacks should be increased to make this really stand on par with the other options. The idea is there, but the balance needs some adjustment.

^ Which means this ability is garbage, so use something else.

What Hideous Resistance truly lacks is, as mentionned above, a grace period between stack losses, like Mesmer Skin.

Add a 1 or 2s status immunity upon loosing a stack, and it would already work much better.

That would also make the base number of stack much less of an issue, since you are probably modding for strength and efficiency while tanking your duration (remember, Mesmer Skin has only 6 stacks at max rank and is still quite OP)

Still, ~30 stacks on high strength builds is workable (tho it can be a bit short with the lack of grace period) as long as you don't spend your days shooting at your own feet with AoE weapons like a monkey. Nothing OP, but if you do your job you should not keep the mobs hitting you alive for long anyway. Still better than having one unusable ability because the stat it needs conflicts with the rest of the build.