Hello! This is a build that I spammed nonstop to hit Divine 1. I can't guarantee that it'll work at any MMR above that!

Though Sniper is usually seen as a carry, he has two very powerful abilities in Shrapnel and Assassinate. With the reworked Aghs upgrade on Assassinate, as well as the change to global assist gold, he can now be played as a surprisingly effective position 4 support. When Sniper isn't expected to right-click like a traditional carry, he can stay out of vision with his long-range abilities, throwing out a constant barrage of damage, vision, slows, and (thanks to the Aghs) stuns. Your team might flame you for it, but I legitimately reached my lifetime peak MMR with this build, so I can confidently say it works at low Divine and below.

I've included details on the ability/item builds in those sections of the guide, but here I'll briefly outline the build's general playstyle.

LANING:

No matter what, ALWAYS take Headshot at level 1. People will flame you for not taking Shrapnel, but just ignore them. Shrapnel is absolutely terrible at level 1 if you look at the numbers, and Headshot ends up providing more slows and damage. Your job for the first few minutes is to harass with Headshots when possible, being very careful not to get killed. If you're having trouble approaching the enemy to Headshot them, take a second point in Shrapnel at level 3; otherwise, take another point in Headshot. Regardless, your build should be 2-2-0 at level 4.

Once you have 2 or 3 points in Shrapnel, you can generally go aggressive and try to set up kills on the enemy, depending on your lane partner. Remember that Shrapnel has a 40 second recharge time until you hit level 10, so only use a charge when you're going for a kill or trying to zone the enemy out of an area.

MID-GAME:

Your primary goal after the laning stage is to get your Aghanim's Scepter as fast as possible. After 20 minutes, your hero just doesn't do much without that item, so it's important to get it quickly. Your secondary goal is to hit levels 10 and 12 as soon as you can. Buy the 10-minute Tome if you can get away with it.

Try to actively join fights in which it looks like you'll be able to contribute; this will help your team out and net you plenty of assist gold. When there isn't a fight going on, try to find a lane that no one's farming (or is too dangerous for anyone else on your team to farm) and Shrapnel it from far away. When possible, stand out of vision and try to soak XP from the waves.

After doing this for long enough, you should finally hit level 12 with your Aghanim's Scepter, and that's where the build truly comes online.

AFTER AGHS:

You should no longer be right-clicking heroes in fights unless you're 100% sure they can't collapse on you and kill you, or you have an item like Enchanted Quiver or Prince's Knife. Your goal is to stay as far away from the fight as you can, while staying just close enough to cast Shrapnel and Assassinate when needed. You won't appear in fog if you never right click, so use this to your advantage. Try to focus your stuns on high priority targets, and spam your ult as much as possible. Try to ALWAYS keep a Clarity active on you at all times, because if you're playing this build correctly, it will almost never get broken, and the mana regen really adds up over time.
Hope you have as much fun with this build as I've had! :)