I played Poppy on ARAM the other day, and I noticed that Barrier had insanely good synergy with Valiant Fighter. When Poppy hits low health, the combination of high resists, shields, and Valiant Fighter lets Poppy soak up deceptively large amounts of burst while wreaking havoc on the enemy team, forcing the carries to flee, and giving your carries time to lay out some DPS. The chaos is even wilder when Poppy lays out a Diplomatic Immunity on the enemy's support and whales on whomever is within clobbering distance.

What surprised me is that the Mobafire builds didn't reflect this playstyle - probably because Poppy isn't popular - maybe even unviable, and reportedly slated for an eventual rework anyway. For the time being, I hope you enjoy my take on the character. Poppy was added to the game long before Barrier, so it's possible that Riot did not anticipate this synergy much, and I think it's worth playing with. I had fun on ARAM anyway and did much better than I usually do in ARAM with a champ I don't know too well.

Pros
* Fun
* Wreaks havoc
* Best barrier bait NA
* Scales well with skillful play
* Pubstomps in the hands of a skilled duo queue
* Strong ball delivery champ

Cons
* Weak top lane phase
* Dangerous jungling
* Inconsistent champ Riot would rather rework than balance as is
* Counterplay options available
* Teamwork-dependent, i.e., horrible pick for solo queue

tl;dr

High risk, high reward champ who has been overnerfed and is slated for a rework. But please do give this build a shot and tell me how it goes! :)

Sheen is the only *essential* damage item, since Devastating Blow is a classic Sheen proccer that scales off of enemy max health anyway. Sheen, some CDR, and the %health scaling makes Q a big threat to glass cannons. You can stop at Sheen or build Trinity Force or Iceborn Gauntlet according to your needs in that particular game. Other than that, stack on the resists, shields, and CDR. Guardian Angel pops you back to life with just the right amount of health to milk your passive a little more, so get it!

If you really want to go nuts, throw in a Guinsoo's Rageblade, but this is a HIGH-SKILLCAP approach. Vamping at low health and depending on Barrier to sustain through teamfights is a risky way to go, but it could work if you're fed or have good teamwork. You probably can't outvamp the damage, but if you think you can, throw in Hextech Gunblade and carry hard. I have my doubts, and I think the tanky + Triforce approach is likely to serve you better most of the time.

You should probably have at least one shielder on your team. A dream come true would be Orianna mid and Karma support. Poppy is a pretty good ball delivery system!

Other than that, protect the carries first of all. Wreaking havoc is your second priority. Make sure your team will be able to get lots of damage in while you force the enemy team to focus you, then ult and/or shield your way out of danger. Flash and then Heroic Charge for an unexpected stun when you can.

You probably want to go top lane, but you might have trouble farming.

You can try jungle, but then you won't be able to go Flash + Barrier. If you have a duo queue with Karma or Orianna, this might be ok, though! Poppy has a great passive for surviving jungle clears, with the downside of vulnerability to counterjungling: stretching out potions to last longer by using her passive leaves her low enough to get two-shotted.

There are downsides either way, sorry. Riot somewhat dislikes Poppy's kit, so they have left her in a somewhat UP state for the sake of game balance. It might still work in a duo queue, and it's still fun!

I admit that I hate top lane and am not a good top laner. But in more experienced hands, she might be good. Here's what I have to contribute:

Her passive depends on being low on health, but of course you have to ward a lot and be careful not to go down to zero. This means knowing your danger zone for your matchup and using potions and Crystalline Flask as needed to stay safe, but not *overly* healthy. It's like a very dangerous game of The Price Is Right, and Valiant Fighter makes it the double bonus round.

That's all I've got to say about laning, but that's what's unique to Poppy, and the rest is just a matter of being a good top laner in general anyway. (And I'm awful!)

But I hope that gives you a place to start.