Well, I just tried Valk Descended, I two-stoned it before giving up, partially my fault for forgetting to use menace at the beginning of the battle but it probably wouldn't have mattered anyway since unleashing everything barely took 30% of her health.
I'll try some other time, with Horus, possibly, but for now I'll stay valkyrie-less. She's just too much for me to handle ):
@Edit
On my endeavours to getting a Valkyrie next time she rolls through, I decided "Hey, I might as well make a Luci Team!"
Of course, that would require two gravities, which means, two heras, which means, Hera Descended!
But amusingly enough, I seem to have 4/5ths of a potential Hera Team just raring to go, between my Drawn Joker and a GOdin, I have a 90% reduction of Hera's attacks, so I'll need 1500 autoheal, Lucifer has an auto heal awakening and so does GOdin, which means the last one could be a Lilith (who is farmable!) and the last two slots could very well be my Echidna (for failsafe) and the Devil Dragon I have lying around (obviously evo'd into CDD) just for stats.
Heck, it shouldn't even be too hard to beat Hera with that setup, 'course I'll need quite a bit more on that team to actually take on valkyrie (Investment into Luci, both Heras, Okuninushi and probably a 'buncle since I'll need some healing for the dual lucinuke) but it's certainly a start!