Overguard (conveniently obtainable via archgun) makes Valkyr immune to infested disruptor energy drain while in hysteria.
Hysteria makes Valkyr unable to lose overguard.
Brief Respite and the Augur set mods can be used to prevent Harrow's Penance from triggering his shield gate. Penance drains shields based on your current shields when cast and the small shield restore from these mods will keep your shields from fully depleting. Augur mods are slightly better because they work in overguard shield ranges.
It's possible, though reaaaaalllly not suggested to clear the entire starchart and quest line with never having changed warframe or weapons. The only blip in this is the excal umbra quest which forces a load out change to complete.
Here's one: today I rediscovered that Nyx can mind control Acolytes, but I'm not sure if it bugs their damage reduction in the same way that Revenant's Enthrall does.
Kinetic Ricochet on any Tetra does strange things inside a Magentize bubble. The weapon does more damage in the bubble with it on in the same way it does more if you put punch through on the weapon, but it does even more if you put punch through AND Kinetic Ricochet on.
Tenet Tetra with KR and Primed Shred is my all-round go to for synergistic projectiles with Mag. It’s not the most DPS, but it’s the most flexible weapon for her. For super high level the Exergis definitely beats it by a lot, but for almost everything the Tetra is great and more fun.
Banshee’s Silence takes precedence over an Acolyte’s Silence, cancelling their canceling of Tenno powers. Has to be running already though. You can’t cast it while being cancelled.
It also cancels all forms of scorpion wires, meaning Infested become a melee-only faction aside from non-scaling MOA goop and flies. I always keep a Silence helminth loadout handy on any frame I regularly fight the Infested with.