Why does Infernus take so long to cast now?
Because he will set a new target after every hit, to prevent he is casting on a dead enemy.
Nope, he still targets dead enemies. Just confirmed it now in Divinion Fields challenge 1, where it is pretty easy to set everyone up to less than 17 combined life/armor before casting Infernus. If splash damage kills a his second intended target, it will still skip that step. Had 3 troops left in slots 1/2/3, cast Infernus. Hit third troop, killed third, killed the second with splash damage, didn’t do any more spell damage, skipping the second direct shot. Then, it skipped to the explode step, which dealt a minor amount of skull damage from the explosion - clearly not another 35 shot from the spell - which failed to kill the first troop.
If the lag is their attempt to fix Infernus’ targeting (which, last I heard, was “working as intended” by not retargeting), then they didn’t follow through. Best I can guess here is that they messed with something global while they were attempting to fixing targeting for troops like TINA, which have the “x random but can repeat” style targeting (Infernus is “x random but wont repeat unless there are no other targets”). I’m talking about the first “fix” that came with the patch didn’t actually fix TINA’s targeting, since the actual fix came later and appears to have removed the lag TINA had while casting as well.
That’s why I wrote “he will” instead of “he is”
As I understood, they plan to fix Tina and Infernus the same way. Not sure, why they left Infernus behind now.
But the lag would make sense, when after every hit the “system” is checking for remaining enemies and is setting his target to this ones.