Oh yeah, true, didn't think about her W balancing the ad... actually W Lv1 is worth the ad marks :o so yeah, ArPen is a good choice :) tho ad marks would double the bonus for awesome early (90 ad Lv 1) ! I think both ways are reliable.

I think we just need to find the tanky/dps balance for items, you can't go full tanky as she won't deal anything, but as going full dps she'll get 3 shotted by enemy carries if not far ahead. Could depend on play style as well.
Maybe some standard crit offtank build could fit ? Like -Mercury Wriggle FM Atma IE Trinity. That would give like 365 AD, 58% chance to crit with a capped 2,5 AS when E enabled, little of tanking (using the MR/L glyphs) and life steal... and free ward :D That does not sound half bad to me ! I'll be trying it.

Hey thanks for the reply and feedback. Yeah the cooldown runes aren't great on her but i don't have the MR per level runes on this account, if you read the runes section i did reccomend the mr per level.
yes for runes i normally go arp marks and flat ad quints, arp scales better so it helps alot early game, the only reason i would take AD MARKS is to last hit easier but with W it's easy anyway.

In my opinion she doesn't work with tanky items, frozen mallet is as far as i go. I've played with alot of other fioras that went warmog atmas and they simply didn't do enough damage as I shredded them down. You're supposed to be a glass cannon, on the carry then out again using the ult to survive she fits the assassin role but has melee carry traits she's a weird one.

For the ult i normally would like to dash onto the carry. ult then do the second dash it normmaly gibs the carry but using it when dropping to aoe is amazing.

Yeah i can't wait too see to get some finalized builds and rune sets on her.

Ok, seems to me your guide is correct but I'll give my opinion...
First, about the runes. I think the 6% CD on runes is unworhty compared to some MR. As a melee champion with no cc, she's gonna need some tankiness. I feel doubtful about the full AD marks & quints, maybe 10-15 ArPen could be useful, filling a bruta's role (the youmuu is a waste of gold on her).
Properly about the items : I like the frozen mallet, it fits perfectly with her MS boost from the E when DPSing a fleeing target and should be suited with an Atma against an ad heavy team.
I think the main focus on her must be getting a high AD and good life steal and/or tankiness. Building AS is, in my opinion, not worthy. AS caps @ 2,500, she has an in-built 1,200 AS boost and like 1 AS base ? So, I think going for the black cleaver is good because of its passive, then the berseker's should be sold for the proper resistance boots at the time you get it.
Also, might be cool to sold the wriggle late game and get an atma. Bit more armor, bit more damage, and mostly the crit !

Totally agree about teamfights. Needs to be played as an assassin, I'd say to wait until enemy team's hard cc's are off or she's gonna get focused and ripped to shred as soon as she's stunned or so. Focusing the carries, off course.
Also I think waiting to be a bit endangered (when you start getting focused and having like 1/2 or 2/3 health still) to toss the ult is a good option. Hardly aimed, life steal procs, and deals quite a good amount of damage. Marvelous :)

(That's my opinion right now, I still need to play and try a few things tho so I might have said a few stupid things :p^)