Editing: A Winner is You! *sometimes*
I've never made a guide before. If someone would like to take what I have here and build on it, go right ahead!.
The Below Build and it's brief explanation have been tried in everything but Conquest (I'm not much of a Conquest player)
As we all know Freya needs a core build and it follows thusly: Shoes of (Magi or Focus) I tend to go Magi on Freya, though sometimes having that little cooldown does indeed rock! Hastened Ring to replace the sorely missed Fatalis, and Demonic Grip is still holding on strong. Last item is Rod of Tahuti.
In my early days of playing Freya 3 years ago, I tried all sorts of builds, and quickly came to the conclusion as with everyone else that Hastened Fatalis was a MUST HAVE. The Ring is not as useful as the old item, however Freya NEEDS that on hit movement buff, otherwise she's forever playing catchup. With the switch over to the ring from Fatalis I've found Freya universaly slower to "come online" in almost all game modes.
Now we work on Lifesteal and the "Pen" Item. Everyone seems to cookie cutter in Bancroft's. I tend to find that if I'm in a loosing battle as Freya, I'm not winning period, and the extra dps with low health is not gonna work in my favour (perhaps some of you disagree) I prefer to go Polynomicon, and start off the battle strong having utilized it's passive by having popped an ability that ends up being a basic attack allows for an "oh shiz" factor on that 1st hit HP drop. Poly may not be as "strong" as Bancroft's, however I find it more useful.
I have always found that I'd die faster than I can dps most gods with Obsidian Shard in my Pen slot, or even Spear of the Magus. This season we introduce Toxic Blade. A "Tanky" item that Boosts all areas that Freya likes or doesn't know she needs, we get an extra 100 health, 10 Pen, 20% Attack Speed and 10% Movement Speed *so she can close those kills* This already screams nice on Freya, then we add that passive, up to 60% Reduced healing when stacked 3 times, and since the meta for almost all builds is to have lifesteal and heals, this item works insanely well in Freya's Kit.
I haven't found anything to really replace Rod of Tahuti on Freya. I understand some players of this goddess play around with her cooldowns and getting faster attacks, and while I haven't personally used it on her yet, I think Spear of Desolation "could" be a good fit on Freya
Actives are always somewhat situational, and while I have popped two into the build they're by no means core.
Beads is situational to your opposing god line up.
For Assault you always always need: Meditation Cloak (always a good unselfish choice for any gamemode)
Aegis Amulet. If you need to pop this as Freya, you should probably embrace your trip to Hel anyways.
Horrific Emblem. This is good to ensure your kills if it's a sure battle. If you have to pop it to chase, you might lose your kill regardless.
Heavenly Wings. To Close your kills. OR Runaway! -situationally better than Aegis.
Bracer of Undoing. This can be a real clinch oh shiz heal if used correctly, and in the middle of a fight (Usually Freya) this can make or break your match. (admittedly I'm not very good at popping this)
As a Freya, I've found you never really get to a point in a game where you need to worry about what consumable you're getting. Either you've snowballed, or nearly snowballed, or are so utterly defeated you're calling it quits @ 10Min.
Freya is a really really risky Mage, either you're great with her, or she's great in a match. Or you're the end of the Peanut Butter Jar (annoying, crappy). I find there is no middle ground for her. As a friend of mine says, she is a "Selfish God" not always beneficial to the team comp. (Like Thanatos). But When she shines, god damn, pun intended.
Select the cards for the main build first. Then you'll be able to add situational builds.