Shendelzare was a Warden, betrayed and killed by Mortred who she trusted in. With her dying breath, she prayed to Elune to grant her a chance to avenge her death. Though her body died, her relentless spirit lived on. Her very presence is an example for her allies, while her enemies fear her determination. Using powers of the spirit world, she can blast her enemies with pure magical energy and reverse positions with others.

Foreword:
This guide would be kept simple and short. Targeted level of play is pubbies.

Skill Build:
Magic Missile: 1, 3, 5, 7.
Stats: 2, 4
Nether Swap: 6, 11, 16
Thereafter max Command Aura. However, if there are plenty of nukes flying around, taking a couple of levels of stats more would be better. I generally skip Terror altogether, but if you like it, I recommend taking it around level 17 or so.
Justification
Magic Missile is maxed asap. It’s a fixed damage spell, so you want it asap, when it’s strongest early. Also, it’s a stun, so apparently you want it. It’s really strong, getting first blood is not that difficult with it if you have great co-ordination with your ally.
Stats because you need them. To survive nukes etc. Also allows you to use Magic Missile more. Besides, early on, getting those level of stats give you more damage output than Command Aura. Also, Command Aura will result in your creeps pushing slightly faster, not what you want. Stay close to your tower, tower swaps (elaborated later) pawns hard.
Swap is taken whenever possible because it’s the skill that makes you feared. The increased in range is extremely crucial. This is the skill that makes you an excellent ganking hero who punishes enemies.

Item build:
BoT/Bottle/2 Bracers/Crystalys/Manta Style
Be the wards supplier if you wish, but be warned, in pubbies, you might be accused of something really unpleasant.
Order of purchase up to individual. However, bottle is extremely crucial. If you are not farming well early, skip crystalys first. Otherwise, Crystalys/Diffusal Blade>Manta Style.

Justification
BoT for map control, round the map ganking.
Bracers to beef up your pathetic HP.
Bottle for rapid regeneration so as to allow you to gank constantly. Expected to rune-whore (elaborated later) with it as well.
Crystalys for some damage. Crit effect scale proportionately as well. Cheap and easy to build up as well.
Diffusal Blade has good synergy on Shendelzare. Swap+Magic Missile+Purge=no hero is going to escape. Manta Style split keeps you alive in team fights by causing confusion. Images have crits as well.

Gameplay:
Levels 1-6: Start off with 2 or 3 sets of tango and Ironwood branches. The side lanes are generally better because you need bottle. Focus on last hitting. Deny whenever necessary though. You won’t be farming much after level 6, so you would want to farm as much gold as possible early. If laned with an ally with a strong nuke or a disable as well, you could try aiming for first blood. Use Magic Missile to soften enemies, before going for the kill, at around level 3. Timely stuns (which should result in some creep aggression) are crucial.

Past level 6, it’s time you gank. If you are confident of getting a kill in your lane, organize stuff with your ally. There are many ways to open your move. You can stun and pound on with your ally, saving swap in case he runs away. Alternatively, you can use swap to bring the enemy close before stunning and pounding on him.

Tower swapping is an art. If any enemy strays too close to you, swap him in. Stun the enemy. If done correctly, you should have your creeps and your tower pounding away. Easy kill. Using this concept, try to force people to stay as far away as possible, possibly even denying them the experience range.

After you are done with your lane enemies, move to other lanes. Fully utilize any runes. Gank and help get kills. After brining down enemies, push the lane and get the free +200 gold. Remember to try and farm a little before moving on to another lane to gank. You are playing in a public game, not IHCS.

Runes usage:
If you have gotten haste, the concept you would be using is the element of surprise. Go in quickly with Magic Missile. Of course, you need your allies to complement you. Swap if necessary. If need be, chase, abusing your haste. Watch your HP when tower diving though.
A double damage rune would be straightforward as well. Let enemy cross river if possible. Magic Missile and have your allies nuke/whack while you whack away too. Hopefully you would get the kill.
An illusion rune would be more tricky. Use it to deceive enemies. Try to convince enemies that you are still at your lane(try to do some last hit/deny with the illusion), while moving your real hero closer to the enemy you want to gank. Remember to stay in fog for as long as possible.
Invisibility is great on VS. Get your allies to bait and have enemies cross or venture as far as possible. Surprise the enemy with a swap, resulting in a tower swap. Judge for yourself then, whether to stun the other enemy or to simply get the one who ate tower attacks and creeps aggression. Usually, if your allies are competent, you can get 2 kills for your team. Magic Missile the other and unload all your spells on the poor fella. The other one, still trying to navigate his way out, should be badly damaged by tower, and hopefully, your allies had soften him up prior to your swap while baiting. By then, Magic Missile would have/or nearly have cooled down. Release it for an easy kill.

When you have gotten diffusal blade, it should be around mid or late early game. Depending on just Magic Missile isn’t going to work. Co-ordinate with an ally and search the forests. If you ever catch any enemy alone, stun immediately. Thereafter, purge at once. Whack away, swapping him back if he is about to escape.

Late game, when engaging in team fights, remember to manta split. Swap, in massive 5v5s, can be used to act as a confusion tool. For instance, a Lina Inverse is about to land a nice LSA on two of your allies. Instead swap her. Another example would be Rexxar about to cast Wild Axe. Swap him so that his axes go awry. Simple concept and trick here.

Heroes you hate:
Spammage nuking heroes. Like zeus, tinker. Also disablers. Like Rhasta. Wait, these are hated by anyone.
K, you hate heroes who can blink/get blink dagger. It makes swap useless.

Good Allies:
You are a good ally to everyone. Bear that in mind instead of asking who is a good ally to you.