As with most heroes, Legion Commander has many different ways that she can be played. Two obvious methods are stacking damage items or stacking survivability. This guide goes with the damage route. I've had great success following these item choices and skill decisions. Following this guide can allow you to have over 500 damage and huge 1500 crits. I've one shot supports late game with this guide. So take it for what it's worth, and modify based on your specific game.
What's so special about Legion Commander? Why would I want to play her? Let's start with the basics.
1.) She can snowball out of control if played correctly.
You know those carries that can just dominate the game if they are fed? Think Drow Ranger, Faceless Void, Timbersaw, Shadow Fiend. Well, Legion Commander is in a league of her own in terms of snowball potential. She has the potential to hit harder than Phantom Assassin, but be much more survivable and useful in fights. Do you want to crit for 1500? Done. Do you want to one hit supports? Done. Do you want to gank relentlessly, but also contribute in team fights? Done!
2.) She has a useful buff for her allies
Press the Attack Removes most debuffs from your allies. Batrider lassoed your friend and pulling him away? Just Press the Attack on your ally and they're free! Did Sven stun your carry to initiate? Just Press the Attack and your carry flees to safety, or proceeds to wreck Sven's face. This spell alone can save your teammates if used properly.
3.) She can jungle very well
Did you get 3 teammates who all called a solo lane? No problem! Legion Commander is an excellent juggler, and good at ganking once she hits level 6. She is EXCELLENT at ganking once she hits 16 and has a few core items.
4.) She's pretty good at defending lanes
Overwhelming Odds is a ranged nuke that can hit an area with a 300+ nuke. This is good for pulling creep waves past your tower when the enemy is pushing. People also tend to fear Legion Commander because they don't want to get Dueled by her. It may be a stretch, but she is one of the best melee heroes to defend a tower with.
5.) She has a 5 second Doom spell.
Her ultimate, Duel, effectively silences an enemy for 5 seconds. This is extremely important when playing against heroes with AOE ultimates, like Enigma, Sand King, and Tidehunter. Being able to prevent certain enemy teamfight abilities can turn the tide of battle. DO NOT UNDER-ESTIMATE THE IMPORTANCE OF THIS!
6.) She is an excellent ganker
Here's a few reasons why she excels at ganking. Overwhelming Odds grants you a movement speed bonus, as well as a good nuke to lower hp for Duels. Press the Attack allows you to remove stuns and snares from yourself and allies. Duel also roots your enemy, mutes them (prevents spell and item usage), and allows a great set up for your teamates, even if you don't kill your enemy during the Duel.
7.) She's very satisfying to play well
When you're able to blink onto an unsuspecting enemy, Duel them to the death, and steal their damage, it just is awesome! This hero is very fun to play and is very versatile. Cancelling enemy utls with Press the Attack is always satisfying.
There is definitely not a set skill build for this hero. You'll need to adapt to your lane. I'll explain each skill choice by build (laning, jungling, mid), then discuss some of the variants based on lane composition later. I'll focus on usage of skills and reasoning for picking in this section.
This skill is not very helpful for jungling. It is nice to have later when you begin ganking, but doesn't help you kill jungle creeps. Of course, it will help you kill a stacked creep camp, but your main problem early on will be mana. It's better to rely on your (mana free) passive and a good hp regen item, like Helm of Iron Will to maintain your hp while you jungle.
This skill is helpful, but not worth maxing out. I get 2 points in this, then leave it. Use this skill when your health drops below 50%. Make sure that you work towards hp regen items, because you'll run out mana pretty quickly from using this skill.
This skill helps you survive in the jungle, so max it first. This plus Helm of Iron Will means that you can jungle no problem. It also helps your future Duels. Max this first, then make an educated decision on which skill to max second.
Same as all other builds: only use on a definite kill, or to lock down an opponent and save your ally.
Legion Commander does not have a set skill build and you should adapt your choices based on your lanes. Below is some help on making those decisions
Overwhelming Odds is your nuke and movement speed skill. If you're in the jungle, when should you max this out? (because I suggest maxing it first when in lane)
1.) You have allies that are good at harassing- If your allies are able to get your enemies hp pretty low in lane, this skill can help you secure a kill. Get it if your lanes are doing a great job and you'd like to help gank.
2.) You are fighting a Broodmother or Enigma. Remember, they can have large groups of minions. This skill does serious damage to a Broodmother with a dozen spiderlings. Not only will it kill ALL the spiderlings, it will do serious damage to Broodmother and give a movement speed boost that is quite high.
3.) You want to kill runners like Dark Seer.This is self-explanatory. This skill can help you kill those enemies that just barely get away every time.
Press the Attack helps you remove debuffs, attack faster, and heal up a bit. Prioritize this skill if:
1.) Your allies have more than one disable- Example: if Rubick can lift your opponent, and then Sven can stun, you may want to run in and right click. Using this skill right next to a disabled enemy allows for very fast attacks for 5 seconds.
2.) Your enemy has lots of dots (damage over time spells)- Warlock's Shadow Word and Queen of Pain's Shadow Strike are two spells that come to mind. If your opponents are repeatedly putting dots on your lane, get at least one level of this. I recommend only one level to keep mana costs low.
3.) There is a lot of nuke/right click damage- This spell is good for quick hp recovery. If you're often getting nuked down or right clicked to death, using this skill might help you survive a bit more.
4.) You're the designated pusher- Legion Commander actually is pretty good at pushing a lane. She can tank all the creeps, thanks to Moment of Courage, and keep all her own creeps alive. This skill also makes her mow down towers. Use it when you are pushing a tower to do alot of fast damage.
Moment of Courage Helps you win duels, stay alive in right click wars, and jungle well. Max it when:
1.) You want to jungle- As explained above, this skill is great for jungling. Even just 2 levels of it allow you to jungle any type of camp.
2.) You want to win duels- It's a double edged sword, since Overwhelming Odds also helps you win Duels, since it simply lowers enemy hp before the duel starts. But this skill remains active during a Duel, so it's helpful in winning.
3.) You're laning against a right clicker- Getting attacked helps trigger this skill. If you get in a right clicking war with someone and a right clicking enemy starts attacking you, this skill can act as a surprise crit and help you win your right click war. Example: you're laning against a carry and a support caster who is out of mana. You begin right clicking the carry and the support also begins right clicking you. You have a much higher chance of winning your right click war with this skill. This may seem like a small thing, but pay attention to enemy right clicking potential.
Duel should always be gotten as soon as possible. No need to discuss the virtues of picking it later.
The builds I display above are obviously not the only way to go. The items I happened to pick are ones that allow you get +280 damage! I gotta tell you, it's extremely satisfying to have enough damage to Duel someone, win hands down, and then proceed to right click the other enemies for 500 damage, critting for 1200. Below is an explanation of my item choices.
Stout Shield This item is very useful and works well with Moment of Courage. That skill procs based on being attacked, so you kinda want to be able to take more hits. Getting hit more means more Moment of Courage procs. Thus, stout shield makes sense. This is a great item for most carries.
Power Treads These boots are chosen due to their high attack speed and ability to help you regen mana. You'll have a lot of mana problems as Legion Commander. It's nice to change the boots to int while you're passively farming just to help you regen. Obviously, tread switching can also help save you mana as you cast your spells. Phase Boots also work well, but lose the mana component. The move speed is helpful, so choose based on your specific game.
Blink Dagger I think this item is required because you'll need a way to get close to your enemy for Duels. The range on dueling is very short, so this is a must. Later in the game, you'll be able to blink onto an enemy and Duel him to the death. This enables you to snowball. Get it at all costs!
Desolator This helps you hit much harder and is relatively inexpensive. If you want to crit for 1400, get this first!
Daedalus This completes your damage build. Once you have this and Desolator, you'll win every 1v1 duel. You can hide in the woods and blink into your enemies. They will fear you and your face melting Duels.
This guide has been primarily about a damage build for Legion Commander. Here are some tips to help you get an edge
1.) Choose your Duels wisely.
If you lose a Duel, your enemy gets some +damage. This is a very bad thing. Plus, they will probably trash talk you about it. It's ok to Duel and not kill the enemy, but not to die during a duel. Practice good map awareness. Duel when you have allies nearby, and try to duel unless the enemy is below 50% hp.
2.) Jungle if things go badly
Legion Commander can jungle very easily past level 3. If you're losing a lane or it's pushed really far forward, duck into the jungle. Use this so that you're always making gold.
3.) Stack those camps!
Don't forget to stack the ancients and jungle camps. Legion Commander can mow down those ancient stacks with simple items. Get your allies to stack them too.
4.) Anticipate the Black King Bar and Blade Mail
Remember that you'll be jumping into the middle of many fights and Dueling. This puts a big "attack me!" sign above your head. You'll find that smart teams always focus you during a Duel or bait you to jump on someone so they can kill you. Getting a Black King Bar and/or blademail can help counter this. If you see your enemy team has alot of magic damage or stuns, get a Black King Bar early! Use your best judgement and anticipate.