Well, if a Bear surrounded by a bunch of writhing, wiggling vines coming toward you with the intent to eat you isn't bad news, i'm not sure what is.
That being said, this build is an absolute bear to get around, giving you plenty of HP and the ability to annoy the enemy team to no end. Speaking from experience, it takes a while to kill Artio with this build, and all her healing on top means she can, for the most part, safely throw herself into the fray and give her team all the time it needs to secure kills or objectives.
Tanky as all get out
You can turn into a freakin' BEAR
Bear puns for days
Hard not to tunnel vision on kills
Anti-heal can be a pain
Her dance from her win screen isn't an Emote </3
Stone of BindingIs personally one of my favorites to get on Artio, with all of her CC abilities, shes basically a pulsing green beacon for team-wide penetration. On top of that it gives her 30 magical and physical protections, which is great for early game.
Stone of Gaia Gives that MP5 you need, as well as all the HP5 and Health you're gonna need for early to mid game. Knock ups aren't as much of an issue for you now, and you can almost always outlast any opponent as long as your team is there to put the hurtin' on em'.
Gem of Isolation This is more of an "I'm already playing a pain in the butt god, why not add more pain?" It helps secure the root on your 3 in druid form, increases the slow from your 3 in bear form and is an all around keeper in my opinion. It also procs your Stone of Binding on abilities that usually wouldn't proc it, like your slash. Oh, did I mention it also adds to your health pool and CC reduction?
As always, your item choice depends on how you can counter the enemy team.
I personally prefer building up lots of Artio's health then giving her items that have equal physical and magical defense, but sometimes you have to get those aura items, or other things to help you watch over your little bear cubs.
Artio can be played in two ways, depending on your team set up.
Initiation; This involves you being a general pain in the butt, landing your roots, slows, and stun while letting your team charge in behind you. You have to be aware of what the other team is doing though. Personally I find it to be a problem that I tunnel vision with Artio, and my teammates suffer for it. So you have to know when to drop back and give that assassin or warrior attacking your squishes the boot.
Defensive; Say you have a lovely assassin, or Warrior that is more prone to taking the initiation than you are. At this point it is your job to tie up any loose ends they may have missed. Is that Bastet getting ready to jump on your squish, or land the finishing blow on your initiate? Nope, because you and your big bear butt just stunned them.
Observe, predict, decide, and execute your plan of action. Be the reaction for their action.