Hello, I'm TornadoXIII. I've played as a large variety of heroes but Tychus is my main and favorite Assassin, with over 190 games played as Tychus.

Let me start this off by saying this is a HARD DIFFICULTY play style if you want to play ranked games, but it's also perfect for casual play. You can't get First Aid with this build, so you need to make sure to be extra careful. This playstyle sacrifices that durability in order to capitalize on Tychus's high damage output and sustainability. With this build you still play like an Assassin, but you also have the power to split-push and capture mercenaries as well as (if not better than) most specialists.

Be mindful of your opponents team-composition and the map you're playing on, this build has a fair amount of flexibility and choosing the right variation can make or break the game.

Take a moment in the pre-game to observe the map you're playing on, and the heroes on each team. This is when you decide on which Heroic ability you're going to take, and plan your talents accordingly.

[*] You can simplify the map-pool into two relevant categories; static maps and mobile maps.
Static maps have "king of the hill" objectives that stay in one particular area of the map. Sky Temple and Cursed Hollow are the two obvious examples, but I'd also classify Haunted Mines and Tomb of the Spider Queen as static maps since you'll be pushing or defending forts with the map's objective. I would recommend the Drakken Laser Drill on these maps because it's perfect for holding down an area.

[*] Mobile maps are much more chaotic, and consist of scattered and fluent teamfights all over the place. Blackheart's Bay, Dragon Shire, and Garden of Terror don't force teamfights to happen in any one spot, and it's much harder to force the enemy team into staying in your danger zone. The Odin's mobility makes it much more useful on these maps.

As for your first talent, grab Regeneration Master if you're on a map that allows you to stay in your lanes for a long time (Tomb of the Spider Queen) or simply makes good use of the extra sustainability (Sky Temple).
If Regeneration Master isn't practical, take Armor Piecing Rounds instead. On Cursed Hollow, for example, you'll typically be spending most of your time running from tribute to tribute, making Regeneration Master a non-optimal choice since you wont be collecting a large number of heath globes.

For ranks 4 and 7, take Vampiric Assault and Rapid Fire every time.

Vampiric Assault will be your primary method of sustainability; a rank 1 Regeneration Master will allow you to shrug off cuts and scrapes, but this talent will keep will be doing alot of work for you. After taking both healing talents, you should be able to GAIN HEALTH by taking a merc-camp. You can take on a Siege Camp w/o losing heath at level 7. You can solo bruisers w/o losing health around level 13.

Rapid Fire is a pretty straightforward choice for a right-click build. If you don't want this talent then pick another build, this is the heart of the right-click play-style. Sizzlin' Attacks also increases your auto attack damage, but I would never recommend taking it. It will give you 50% higher attack damage for 5 seconds and rips through your mana really fast. Rapid-Fire boosts your attack damage by 45% passively, all the time always. The only exception is that Sizzlin' Attacks boosts the Odin's damage but Rapid Fire does not boost the Odin's attack rate. However, a slightly stronger Odin is not worth cutting your damage (and thus your healing) and burning your mana all game long. Rapid Fire will keep you on the battlefield: Sizzlin' Attacks will keep you channeling your hearthstone.

After you pick your Heroic Ability, the next choice you have to make is your level 13 talent. Many players take Problem Solver, but I would recommend taking Stim Pack instead for many reasons.

1) Evasion: Whenever you're fleeing, the speed boost will save your life more often than not. You'll be able to out-run most threats, and if you can't shake'em off alone (Illidan) then this will shave a few precious seconds until you reach the safety of your allies or your structures.

2) Chasing: None will be able to flee your wrath, you can use the speed boost to your full advantage whilst channeling Overkill, allowing you to easily gain ground on them, and then whip a grenade in front of them to knock them back. A must-have for securing some easy kills; This talent allows me to even chase down Valla.

3) Base-Raping/Merc-Capping: Even if you just want to use Run&Gun for the wind-up, you'll still see usefulness with the attack speed boost. You want this talent primarily for the added mobility, but the damage boost is a great side-effect that happens to fit the right-click build very well.

NOTE) RELENTLESS: Depending on the composition of the enemy team, Relentless may be just as good at keeping you alive. There are many heroes out there with stuns, roots, polymorphs, etc. It can counter many heroes fairly well. If you keep dying to these kinds of debuffs from the enemy team, consider taking Relentless instead. Unlike Stim Pack, Relentless works while inside the Odin, so that's worth considering too. I'd take stims most matches but sometimes this one is a solid choice too, use your judgement.
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Rank 16 you want Stoneskin. Pure and simple. Whenever you're in danger, pop the shield and extend your healthbar. IMO this is better than the other level 16 options, pure and simple. It's a major survival tool for team-fighting, winning 1v1 duels, and surviving the random ganks.

If you're playing on a "static" map, get Focusing Diodes at level 20. It's a great talent that will drastically magnify the effectiveness of your Drakken Laser Drill, and the value is too high to skip. It's incredibly good at locking down a huge area, perfect for the "static" maps where you can best punish the enemy team for fleeing. Incredibly good at pushing with your golem if you have a big golem, and is also great at burning down the enemy golem if you need to play defensively.

If you're playing on a "mobile" map, seriously consider Nexus Frenzy. The range increase will help keep you just that much farther away from harm, and increase your damage (and thus regeneration) to boot. It also buffs the Odin's range and rate of fire as well, so it works great no matter which heroic power you chose. Combined with Rapid Fire, you'll be raining lead like a true bullet hose with almost 7 attacks per second, 8/second during the stim-pack bonus. You'll be ripping down buildings like it's nothing with right-click, dealing 700-900+ DPS to your target. Don't bother using Overkill at this point unless you're chasing or crowd-clearing, even with AP Rounds (level 1) your auto attacks will have significantly higher single-target damage.

If you grabbed Odin, I wouldn't ever take Big Red Button. Sure it makes for a better Odin, but the Odin is good enough already as is, and the extended duration is more of a drawback since team-fights are usually over within the un-extended duration anyway. Nexus Frenzy is a solid buff that boosts all aspects of your game-play and, as already stated, it still makes a better Odin anyway...