Should this site change to EDOPRODECK? Hmm. Anyway the recent EDOPRO (previously YGOPRO Percy) simulator now can work with Mischief of the Time Goddess, making playtesting full power Valkyrie with future/prereleased cards possible. Basic combo is to OTK your opponent using Time Goddess (double battle phase) or Borrelsword Dragon for easier setup. Going first, we can make Apollousa or True King of All Calamities from Diviner of the Heralds. The combo is normal summon Diviner, dump Trias Hierarchia, use Trias tribute Diviner ss Trias, use Diviner ss Sechste, use Sechste ss Sigrun, overlay Trias and Sigrun for True King of All Calamities.
The Valkyrie cards ratio is medium because most of them are not too good, only some you wanna see the most, also we dont rely on Ride of the Valkyries that much as it makes our monsters shuffled to the deck going first (doesnt even worth the no damage taken for 2 turns). One copy of Time Goddess because its searchable and mostly a dead card (we can OTK with Borrelsword anyway).
The supports: Hecatrice + Valhalla, Hall of the Fallen (free fairy, triggers our Sechste too), Galaxy Cyclone and Night Beam (backrow pops, work with Vierte as both are normal spell, similar to D-Hero Diamond Dude but faster), One for One (for Sechste, Vierte target), Raigeki and Herald of the Abyss (monster pops, Vierte target, we didnt play Lightning Storm as it conflicts with Valhalla), double Dark Ruler No More (only 2 cus while we can do 2 battle phase, this card makes us unable to OTK cus no damage on first battle phase), Reasoning (mainly for Sechste, our Valkyries have different level too), Pots (can be Desires, Extrav, or anything, Valkyrie deck needs so many draw/search cards as much as possible), Monster Reborn and World Legacy Succession (extender, possibly triggering our Valkyries from GY), Tuner's High (Diviner searcher by using Sechste as fodder). Can put Utopia Double if you want but it will be very dependent on our hand.
Extra deck: We're using Extravagance, means multiple copies of our important cards.
Pros: Going first is much stronger than previous build, have multiple ways of OTK (more if with Utopia Double), bunch of removal/breaking board cards, can put in handtraps.
Cons: Only has Diviner as great starter (other ways we might need extenders), Ride of the Valkyries is very bad on first turn (it means drawing multiple Valkyries going first is kinda bricky sometimes).
Cards to think of: Honest (great card but dead going first and we can just remove opponents monster anyway), other Valkyrie related spells (some arent that good and some only provides small advantage), Parshath supports (the link 3, the level 9, and the continuous spell can be good in recycling our Valkyries if we play grindy games)