Alright there are three things to consider when picking between these choices.
-How Anath is viewed by the Seraph as a result.
-How Helel training them make them favor him. Because it might be across the ashes of a pantheon, or four, but the odds of Helel not rebelling seem low, which unless we're planning to fall from Heaven is an issue.
-The actual utility of Anath training the Seraph in question.
[ ] Metatron, Messenger of Heaven.
-This has Anath repaying Metatron for what he did, and
-Considering Metatron is in command of a bunch of messengers there seems little utility for teaching him how to command the common angels.
-There is considerable utility in the chief messenger of Heaven being capable of fighting his way through whatever gets in the way of his mail run.
[ ] Sandolphon, Heaven's Song.
-There is the possibility of Anath picking up on some of the grace, but she is rather small iirc.
-A giant Seraph would make for a rather potent commander of angels, and thus there is utility in Helel teaching him.
-The utility seems for Anath seems less than her older brother imo.
[ ] Sariel, Caretaker of the Earth.
-This smooths over some issues, and that isn't something to ignore, but we're in the business of removing a pantheon, or four, which means we need to be frugal with Anath's time. Also there is affinity issues.
-While Helel will plausibly cause issues long-term for the immediate future Sariel learning how to command her flock when the other pantheons target them while undertaking their duties will prove invaluable imo.
-So the utility of this option Helel outweighs Anath imo
[ ] Remiel, Herald of God's Wrath.
-There is massive synergy here as Remiel can with the proper tutilege by the tip of the spear for the army of heaven, or at least the strategic bombing campaign to weaken a foe before host of Heaven kicks in their door.
-There is perhaps a degree of utility of Remiel can learn how to coordinate his subordinates.
-The utility for Anath teaching Remiel far outweighs Helel imo.
[ ] Take out the spears from above, does it really matter if you don't know who they are? they can't match you.
This seems like it won't really teach them anything beyond "get good scrub", and thus seems rather pointless.
[ ] Stop the mages on the ground, Baraquiel and his mages are a significant enough force that if they were to keep it up they would not even need Kokabiel to distract you.
This teaches our mages the concept of gank the magic user before they have a chance to do stuff, and thus will prepare them for this eventuality. This is especially useful if we're planning to face a pantheon with someone on the level of Father.
[ ] Push the advantage onto Kokabiel, he is likely to chase you no matter where you go, at least here you can stop him relatively alone.
This removes a weakness for Kokabiel before he gets a bunch of people killed. Although I don't recall him being a direct subordinate of our own.
[ ] Let them win, It's only a test after all, not a real battle, Father taught you that mercy was above all other virtues. The likes of Ra and Shiva would give them no quarter, so you shall prepare them for such fights by crushing them.
The Star Hungers.
I'll be blunt pick this if you like tragedy, and want to see Anath be stabbed in the back by her subordinates in the future. Because while this will certainly get them prepared I'd say the part about the Star is it consuming the bonds of comrades that would normally exist in exchange.
For this there are two factors to consider.
-The removal of a future threat be it raw potential, or the possibility of forming a unified front via social connections.
-How it hones the Heavenly Host for future campaigns.
-Overall notes.
[ ] Zeus's pretenders and all of the peloponnesian lands, may his sky fall around him.
-In terms of raw potential they pose a serious threat, but for social connections they're a new pantheon meaning while somebody in say the Jade Emperor's Court has a connection with them they're somewhat isolated.
-Also they're a new pantheon meaning while the defeated the Titans in terms of honing the army assigned to Anath they're liable to not be the best for actually testing the Host.
-In general I'd say due to their potential we absolutely want to take them out second, but they're something we afford to not take out first imo.
[ ] Ra's children of the Nile and their human playthings, may the false sun be eclipsed.
-In regards to potential they've already realized most of their own already, and are noted to be the closest to a peer of Heaven barring Father. Furthermore they've been around long enough they've pretty good odds of having connections with other pantheons, and thus they're liable to react in a somewhat speedy manner as one pantheon has been wiped out. So I can see them actually being proactive in preparation for a battle after ten years if we go after somebody else nearby due to proximity with Babylon.
-More importantly the noted advantages the Host given to Anath by Father has over them basically makes them perfect for honing the Host into a proper army that functions as a unit. Basically Anath is uncertain she can defeat Ra alone meaning she'll get used to the concept of having backup something invaluable for character development, and punching up against other pantheons, which is before factoring in the edge our magic has alongside them having more heavy hitters.
-Overall this is the best option as a near peer oppoent will force everyone to work as a unit, and based upon the amount of punching upward we'll need to be doing in the future getting used to doing so is a good idea imo.
[ ] The Jade Emperor's Court and his useless magistrates, may their arrogance be their downfall.
-They're noted to have 3 peers to Father, but their detriments means we can hopefully leave them alone.
-Rather than honing the army the power difference without any actual experience in battle is liable to at least severely harm the Host.
-Bad idea as they're liable to be slow to react, and actually killing them all will be bad for morale as there are loads of them.
[ ] The Trimurti and their Heroes of legend, may their creation be devoured.
... I'm just going to say picking this option is
foolish, and leave it at that.
I might expand upon these points more if anyone has questions, but it is getting late on my end
[X] Metatron, Messenger of Heaven.
[X] Remiel, Herald of God's Wrath.
[X] Stop the mages on the ground, Baraquiel and his mages are a significant enough force that if they were to keep it up they would not even need Kokabiel to distract you.
[X] Ra's children of the Nile and their human playthings, may the false sun be eclipsed.
The two Seraphs best suited for getting better personal combat ability as Metatron will need to carry messengers around to insure the coordinate against the opponents heavy hitters is maintained, and giving Remiel an increase in personal fighting prows will allow her to be far more aggressive in preparation for the proper campaign.
The reason for the mages is preparing them for taking on a heavy hitter as we're going against a pantheon with a bunch of them, and thus doing so will save lives imo.
Because this removes a pantheon that seems rather reactive, and more importantly is a foe well suited for preparing the Heavenly Host for going through the grueling war that is to come as a Team. This is incredibly important as there are pantheons that basically require that for us to overcome them without taking on unsustainable casualties.
