-AoN-CanoLathra-

Ivara is the pick for sure, the other two are farmed deterministically through a quest. Both quests are a bit of a slog, but they are nothing compared to trying to get the Ivara parts from the Tier 3 spy reward table.

Dual Toxocyst are great, and the Miter is also a lot of fun. Not the strongest launcher on paper, but its ability to seek out targets before then exploding into sub-munitions that seek out more targets allows it to clear packs quite well. The Ceramic Dagger is currently the most broken pseudo-exalted statstick in the game, the Lex Prime is now the newest and strongest incarnation of the Catchmoon, and the Lato Vandal is pretty good for clearing out crowds. Strun and Torid are still definitely the most powerful of the incarnons, though.

Are you making sure that the enemies have at least 5 different status effects active when you kill them?

Yeah, after recent patches sometimes nullifiers will enter a bugged state in which their bubble was destroyed "too quickly" and it acts as though the bubble is still active, preventing all AoE and Ranged damage from damaging the nullifier. The reason why they seem to randomly come out of this bugged state is because the bubble isn't there, so it can't take damage, and after a few seconds of not taking damage, the bubble expands back to its smallest size, at which point it takes damage and the bugged state is resolved. Would really like for DE to fix this bug as it does remove all of the counterplay that these enemies are supposed to have.

As the highway robbers in Oblivion put it: "Your money or your life" You either slowly grind away, one forma per day, and optionally also grind the Lua puzzle for hours upon hours every day to get another one. Or you buy them for Plat. Those are your options.

They aren't supposed to, but rarely they can. It seems to happen when an enemy eligible for an enemy-specific drop (riven slivers from exemi, thrax plasm from thrax units, etc.) dies after the current objective has been completed but before the transition to the next area has begun. So with a fast transition speed it never happens, but if you are playing with other players and one of them is slowing down the transition, then there's a chance that some will drop.