Regarding the Tzeentch Soul Grinder change: the way it's always worked is that the "javelin" they throw is essentially five small projectiles fired in exactly the same arc which is still how it works against SEMs That "Javelin" is considered a guided projectile. And since it has multiple projectiles, it benefits from the change to those sorts of attacks introduced in 5.0. Hence the spreadshot against multi-entity targets
Archaon is notably overcosted when just comparing his combat performance for the cost. He's strong, but there are much cheaper lords that can out-fight him and provide simlar or better support, and pairing with another sorcerer that's also paying a "tax" on their combat stats for the ability to cast spells is doubling down on that wizard "tax". Doing this sort of double caster build is basically cutting the value of Archaon in half, since you're not getting much from his spells, and being a strong hybrid is what really lets him be a competitive choice (albeit one that's vulnerable to sniping because his health isn't particularly high). If you're just looking for a mounted fighting lord to pair with healing, a Chaos Lord of Nurgle on rotbeast is about as strong as Archaon and is significantly cheaper and provides excellent battleline support with -40%-55% WS (It's possibly a bug, but the icon item is able to start stacking up again and applying the 1st and 2nd levels of its effect without dropping the 3rd level of the effect that has infinite duration, because the Nurgle lord with it reduces WS by more than 50% sometimes). Or you can go for Kholek, who's again stronger and cheaper with more HP. Just taking a sorc lord could very well be the way in this match up though. I don't see much need for an expensive/powerful lord vs Daemons. That or Valkia to help put pressure on changebringers, since they're a unit that WoC has very limited options against. Valkia/Tzeentch disc characters are likely the best options for going after them, since marauder cav range is too short to rely on, and doom knights are quite a bit more expensive and more vulnerable to horrors shooting in from the ground.
Medusas also do spray shots against multi-model units now. I tried it against Bloodletters, and the first shot took them down to 60% HP. Granted that it's an ideal target (tight formation, low armor, phys-res negated by magic shots) but still. Even Dwarf infantry get seriously pummeled by Medusas now.
It looked like the first burning head was also sub-optimal, it tagged the Sourguts and seemed to miss everything else (which allowed the Sourguts to ignore it once their shields came back) but that might have just been the way it drifted after being cast.
Turin, what's that new green icon on HP bar on regenerating units? Does it tell how much HP they regained or it's just here to indicate that unit has regeneration?
i like that the range units got buffs same with the medusa model but both of them need like some slight nerfs i hope they keep the buff but nerf it some, its to many kills atm for soul grinder and medusa.
1:50 Specifically CA reworked the tracking on any seeking missiles, they will now target randomly selected entities in a unit when able as opposed to all of them targeting the same one This buff to the tzeentch soul grinder was likely unintentional as the fix was originally intended to help the hawk riders ability on campaign as the sisters of twilight