Rat Cage + Carrion Call tech for fastest SRS popcorn. Worth it? Some napkin math inside

So, SRS popcorn is a pretty interesting (to me) build vector because of how good SRS feels to play: placing the summons wherever you want is easy, it's naturally homing, and the explosions are satisfying. However, there is a significant problem: Compared to PoE1, there isn't much you can do to speed up how fast the spirits pop.

Of course, there's the fireflower tech, but that requires a low level SRS and thus is only really suited for Cast on Minion Death builds, and those have a very different set of build constraints, having to figure out how to scale our own damage, how to sustain mana, etc.

I'm mostly interested in the life scaling SRS popcorn style where the damage of minion instability is what you're trying to increase. Here's the long and short of it:

• Flame wall seems (in my testing, but I may be wrong there) the fastest and most reliable way to summon raging spirits.
• You generate 5 spirits per cast, so two casts hits the limit of 10 spirits. This means your cast speed must be half of the spectres time-to-explosion, which is how long it takes them to 35% life. It's important that cast speed remains slightly slower than this value, otherwise it becomes possible to overwrite spirits that haven't yet popped and the build feel degrades a lot.

By default, spirits take 20% of their life per second due to Infernal Legion, increased to 24% by Feeding Frenzy. To pop, they must lose 65% of their life, which means they pop in 65/24 = 2.7 seconds. This can work with a cast speed of up to 1.35s, which is unfortunately extremely slow.

The main tech I know about to speed this up is to use Rondel of Fragility with Necromantic Talisman. This reduces the minions' resistance from their base of 0 to -30% (won't assume corruptions to keep things simple). This would increase their damage taken by 30%, bringing the time to death to 2.09s, and thus the optimal flame wall cast speed to 1.045s. Still way too slow.

So... I was looking around for alternative approaches to reduce their time to death, and I stumbled upon one that, while a bit wonky, could work well. The idea is to significantly tank our own fire resistance, and then use the Rat Cage combined with some source of ignite immunity to actually survive fire damage, plus carrion call to have our SRS copy that fire resistance.

The most practical and least convoluted sources of reduced fire res I found are Ventor's Gamble, Controlled Metamorphosis and The Hollow Mask (which incidentally has good synergy with Rat Cage). Without taking any of the fire res rewards during campaign, it should be possible to easily achieve -150% fire res (-60% base at endgame, say 30% from the gambles, 10% from the mask and 20% from metamorphosis). Of course this could be taken even further with Ingenuity, but let's not get carried away yet.

With -150% fire res, the SRS would be taking 1.06S to pop, which corresponds to a maximum cast speed of 0.53s.

I feel like 0.53s is a nice value for flame wall, and the build would feel fairly smooth to play. Now, the question is: is it worth it? Seems like surviving all fire hits through rat cage may be a tricky build requirement, though it works well together with hollow mask. Ultimately though, 10 pops a second while being able to utilize Fireflower to significantly boost SRS level (no need to sacrifice the amulet slot to the Rondel tech) could be worth the difficulty.

Thoughts, or ideas on how to improve it?