*** The guide template is trolling me hard, read below for core, starting, and optional items ***


Hey everyone, this is my first guide. I'm not a pro player, I don't intend to tell you the best way to do anything (especially on a new champion). This is what has been working for me on @PI. Try it out, pls do comment if you have anything constructive to say be it positive or negative. Thanks all and game on!

Overview:
As Atomic Poison Ivy, you are going to get through the jungle at a pretty decent pace, safely, and be able to add some crowd control to ganks in the meantime. Invading the enemy jungle is usually pretty safe because you can tank a lot of damage and easily escape back into your own jungle if you need to. Your poke is annoying and safe, and you don't need to get into hard engage situations unless you want to. You'll never be bursting champions from %100-0 though, and mostly your ganks are about locking the target down and adding what damage you can. If you want to carry the game on your own, take an assassin jungler or maybe batman/shazam. Ivy is about controling when and where to engage, surviving through huge damage, and letting your team clean house.

Amps:
Lex and Star Augs giving Power Damage and CDR, both flat and per-level. Gives 10% CDR lategame. I haven't tried out other augs yet, once i get the items and timing down I'll update this part. I'm thinking early Power Damage and scaling Power/Attack Armor is going to work.
Mods for Early Medsys (Medusa Mask), Phantom Strangeler's Necklace (+10 max stacks), and Cosmic Staff (Disintegration 2). Keep yourself from dying, which is usually pretty easy on @PI, and keep stacking up the Necklace. The armor means your passive stays up longer, which means you get more damage on your Q, which means you clear the jungle faster with more HP and Will to spare. Always make use of your passive, it's everything for your early jungle.

Starting Items and Build:
Medusa Mask (2) and a Maurader Shield. You will be able to jungle indefinitely as long as you are using your passive properly (let it come back up between jungle camps).
Make sure to get Stangler (1) as soon as you hit 250 credits and upgrade it to level (2) after your next 750 credits. Once this starts stacking, you can cc and walk right up to marksmen to use your Q. They will get through your passive and then start running when they realise they can't hurt you (unless someone fed them early).
I've been going for Cosmic Staff second. Tanky damage is good. Health, Power, Penetration, and a good passive. Ups your damage so that you stay relevant. If you dont start adding some damage to your build at this point then the other team can mostly ignore you. If you team is very coordinated then you can probably skip out on the damage until later but this is usually a good time for Cosmic Staff (other damage items might work here also, I'm trying out alternatives at the moment). 
Next is Fragment of Mogo. The Attack Armor is pretty key in AtPI's kit, scaling on both her passive and her ult, the health is essential to making the armor worth it in general, and the active is awesome. Given her root and slows, you can often keep people in the AoE active for several seconds. 
The next couple items will depend on how the game is going and what kind of damage you need to worry about the most. It's easy to look at @PI's kit and get really invested in Attack Armor, but you can't ignore Power Armor if the other team has a strong blaster or a strong Mech WW. You might have to go Entropy Aegis or another Power Armor item next. Olympus Gambit is alright if you are getting hurt by mixed damage or burst damage in general while fighting for relays. If not, go Metallo.
Metalllo's Heart is awesome. CDR, add more Attack Armor and Will, and you end up really hard to kill at this point. The mod to upgrade Metallo's passive can be good, but I don't find myself using it as often. Again, in a draft pick game this mod could come into play if the opposing team had a couple attack speed scaling champions (cyborg, gasbat, batman prime, etc).

Other Items:
Helm of Fate, Olympus Gambit, Suit of Sorrows, Entropy Aegis. They can all work depending on the situation at hand. Try them out, try getting the core build items at different times, try one of these while you are still building core, mix and match. There isn't really any one build path or build timing to stick to from one game to another. Observe the guidelines, make adjustments on the fly, see what works for you.

Skills:
Q is your jungle clear and it does +100% of Power Damage if your target is affected by Ivy's Toxic Growth passive. Your passive also gives you a shield if you are not attacked for 10 seconds. In between jungle camps, there is just enough time to get your passive back up again for free damage absorbtion, AND to cause Toxic Growth on the jungle drones so that you get bonus damage on your Q. This is really important for her clear speed and willpower efficiency. Always start a jungle camp with an auto-attack so that they attack you and get Toxic Growth, then hit them with Q for the free damage.  The non-elite camps usually get through your shield after 2-3 hits, so you get full Q damage on them the first 2 times, after that you get the bonus damage on every other Q (one to set up TG passive, one to consume it). Always position yourself so that your Q hits all the drones in the camp. Using your W or E to clear jungle drones feels a little wasteful and they are both on long cooldowns, meaning you might miss the opportunity to gank, or escape an invade, or poke an invader away, or harrass an opposing jungler, and so on if you use them for jungle clearing. After you build up your CDR, or if there is no opportunity to harrass or gank, you can add a little speed to your clear by using them on the other hand.

Ganking:
Use W to root and apply Toxic Growth, then land E on them (might have to lead them a little) to slow and silence. Close into range for Q and auto-attacks if you want to hard engage. If the lane you are ganking for has any root, stun, slow, etc, you can get a ton of damage onto someone before they have any opportunity to escape. Your E persists for a few seconds so place it wisely to cut off escape paths. More on this later.

So that's it for now, let me know what you think and I will continue to update this every couple days until I feel I've really figured out all of this champion's strengths and weaknesses. Thanks everyone, game on!