Level 1: Shadow walk
Level 2: Jinada
Level 3: Shuriken Toss
Level 4: Shuriken Toss
Level 5: Shuriken Toss
Level 6: Track
Level 7: Shuriken Toss
Level 8: Shadow walk
Level 9: Jinada
Level 10: Jinada
Level 11: Track
Level 12: Jinada
Level 13: Shadow walk
Level 14: Shadow walk
Level 15: Stats
Level 16: Track
Level 17-25: Stats
Justification : Shuriken toss is maxed first, because at level 7, 325 damage nuke is one of the highest damage spells in the game. Yes, it scales badly, but it's just too good to miss out. Next to max is Jinada, and not Shadow walk. Why's that? Because to set up ganks, you don't need a 60 second invis, you only need 20 seconds to move between jungle->lane and 120 damage isn't really that good compared to bigger crits and lower cooldown.
Drums is one of the most stat efficient items there is, granting 63gold/stat. Gives you MS, AS, gives you HP and mana.
If the enemy team is full of nukers, get that strength treads. If they're full of quick moving heroes, get those phases. Adjust to the situation
Stout shield will be necessary to withstand harassment in lane and later to upgrade it to PMS. What you will need to do in lane is farm up to 300 gold, buy that PMS. If your lane has a bunch of heroes that use mana, consider selling one branch to buy yourself a magic stick. If not, just buy boots and upgrade into wand after. Your main priority at laning stage is to get to level 6 as fast as possible. You don't need many items early on, so you can just stand in lane not dieing, but also grab a creep kill anytime you can.
So, after those pesky 7-8 minutes, your inventory should look a something like this
and level 6. Now is the time for you to move on - Leave your support on the lane, or if possible just kill the person who's on the same lane as you. For a ganking route, I usually pick mid. Your mid hero should be level 7-8, so you two will over power anyone in mid. Wait for enemy creeps to push to your tower, go invis from the high ground, hit, track, shuriken, dead mid hero is dead. 250 damage nuke at minute 8 is a lot, so you should max it . Yes, it scales quite poorly, but it's just too big to miss out.
After this gank, your inventory should look like this
Continue ganking, while your main carry is ricing it up. Organize ganks with your team, communication is essential. Don't forget to track those kills!
Time to go to the mid game.
Your item set should consist of these items :
Now, use your items wisely.
This is the time where the opposite panda got a blink, enigma got a blink, roshan is down. What do you do now. This isn't a whole DotA guide, so I'll leave out the warding and positioning. What you, as a Gondar must do, is check the enemy teams itemset. Do they got a gem? Maybe you ran somewhere while invis and the enemy creeps attacked you. This is the part where everyone is buying dust/sentries, so you NEED to concentrate. No more running around in the enemy jungle, no more running past towers. Now you stick together with your team. Use your windwalk to scout for enemies, if you see a glimpse of a hero, ping on the map and tell your initiator to go there. Stay behind your team. The battle begins. Don't pop out yet, wait till one or two dusts are usedthen go around the backline. Now, think : what hero can be bursted down so fast that he won't notice? Focus that hero down and then continue your spree on the supports throwing track on random heroes.
Late game items:
Now that you got your core, you proceed the 2 routes :
Does the enemy team have heavy magical damage? Make
Some one too tanky and you need more burst damage
In the late-game situation, don't initiate first. Let your initiator do that. After that, don't pop up from invis! Wait. Wait for the best moment for you to appear. Oh how many opportunities there were for me to just come in and die, because enemies were ready for the initiation, and used several dusts in hope to find me. But no, I've waited, waited until my chance was right. That's what you should do too. But, don't stay invis all day. Throw those tracks, they do matter even in late game situations.
Your primary targets are the supports, the semi carries. They should fall quickly, after that just continue what your team is focusing.
You're a sneaky hero. Do some sneakiness. Don't run the way they expect you to, run the other way around. Don't stand near them, stay behind them. ALWAYS CHECK THEIR INVENTORIES! How many BH's have I seen that just ran into gems, and then pinged 1000's of times "PUDGE GEM!@!@!". If you have just looked at their inventories, you wouldn't have died.