Few roles are as unknown or as misunderstood as the solo-laner. In fact, "solo-laner" has even become somewhat of a misnomer, as rarely are they 1v1ing people anymore. Rather, a more accurate term is the "off-laner" because their job consists primarily of gathering XP and clearing waves in whatever lane the rest of their team isn't. This is a general guide to understanding this role.
The most important part playing an off-laner is thinking like one. Are there minions not being soaked? Chances are you should be there soaking them. Is objective up? Is your team fighting? "Too bad" is often the answer you'll need to give yourself. The minion genocide is more important. Now, this is not a free pass to never join your team. Grouping is still extremely important for objective and ganks, but there are times when you should not join your team and is actually detrimental to do so. There aren't really any universal rules for when or when not you should group, it is going to change on a game by game basis by a huge number of factors. It's something you can only learn from experience and study from watching good off-laners play.
For rules of thumb, though, the later the game progresses the more you should group with your team because objectives become more powerful. By level 20, you should hardly ever split (except for catapults) as talent advantages no longer exist. If your team is ever behind a talent tier, you should probably avoid fighting altogether (unless you have a man advantage) and try to soak as much XP as possible to catch your team up to the same talent tier. Your primary goal, after not dying, should be to obtain as much XP as possible for your team. XP advantages translate into talent advantages, and talent advantages win fights, which win objectives, which win the game.
Your number 1 priority in the off-lane is this: do not die. Dying is particularly bad for an off-laner; not only do you give the enemy team XP, your team is likely to lose XP from enemy minion waves, and your 4-man will have to rotate someone over to cover your lane. This is extremely detrimental. If you are threatened and might die in lane, it is literally better to stand behind your gate and simply let your towers take damage than it is to step out and die. If you need to soak in a dangerous place, you can try to soak from a bush and never reveal yourself, and simply let the two waves kill each other. If there are multiple enemy heroes in your lane, I defer you to CavalierGuest's video about this.
Though waveclear is not the defining trait of an off-laner, the meta has shifted (though note it may shift again) so that waveclear has become more important for an off-laner to have. The reason why waveclear is so important is twofold: first, since the 2018 gameplay changes minions are terrifying siege menaces and are now significantly more dangerous threats to structures, and therefore have to be dealt with. Second, clearing a wave allows you to quickly rotate to do something else on the map. Waveclear enables rotations. High waveclear off-laners such as Blaze or Leoric can even double soak on many maps. They can catch all of the XP from multiple lanes by themselves. Other uses of rotating include ganks, or possibly aiding in mercenary camps.
Waveclear doesn't just enable the off-lane to rotate. The same concept applies to the rest of the team, too. Hence the popularity of the 4-man rotation. A double soaking off-laner can allow a team to 4-man group to possibly push a lane, steal a mercenary camp, or setup ganks. Make sure to communicate with your team whenever you try to double soak or soak specific lanes to free up the team. Sometimes teams at lower ranks will not even know that double soaking is a thing until you tell them about it.
For both double soaking rotations and 4-man rotations, one side will be ahead and the other behind in the rotation. What this means is basically one team will clear faster than the other, and therefore rotate sooner. This has some creative applications for use. For example, if the objective will spawn bot lane, and you are well ahead in the rotation, you can set up a rotation in such a way that you go from top to mid to bot, while your opponent either has a choice after clearing mid wave to catch your top wave that you just pushed in, or going bot for the objective.
While perhaps not as common in the current waveclear meta, an important part of off-laning is understanding how to deny soak, or when you are being denied soak. Simply put, this is usually done by bullying someone so far off of your wave that they cannot get close enough to soak the experience. This is something that old Thrall excelled at. He had so much damage and sustain that if anyone tried to soak he could efficiently trade into them, effectively forcing them off of soak. This is often done by freezing the lane closer to your side of the map to make it more difficult to soak.
Another common way to deny soak is allowing your minions to die when no enemy is within soaking range. If enemy heroes are absent in a lane, you can often push up your own wave so it will die to towers, denying all of the experience. If, however, you know an enemy will be rotating soon, it may be better to simply not clear at all and let the enemy wave kill a minion or two from your wave, denying those minions worth of experience.
Something many HotS players are unaware of are common wave manipulation tactics, and there are several powerful and basic wave manipulation tactics that you should keep in your toolkit:
Freezing Lane: Of all lane manipulations, the most important of which is being able to "freeze" minion waves. All this means is instead of clearing the wave as fast as possible, you intentionally don't kill enemy minions in order to force the lane to stall, or "freeze." Being able to freeze a lane so that tower range exactly covers your minion wave and not the enemy's is a powerful tool. It forces your lane opponent to overextend to soak and, if they are a melee hero, makes it so they cannot clear your wave without taking tower damage.
Prepping a Lane: The ranged minions do by far the most damage in a minion wave, and so you can prepare or "prep" a lane to be pushed by only killing the enemy ranged minions. What this will do is stall the lane long enough for a second minion wave on your side to spawn, with the first wave remaining alive. This creates a lane imbalance that can push up a lane and begin to do structural damage. If you can combine this tactic with a mercenary camp or a boss, it becomes a major pushing tool and a huge problem for the enemy team.
Tanking Ranged Minion: Perhaps not a wave manipulation per se but still an important tactic. Another way to help push a lane up is by walking close enough to the enemy minion wave that you aggro the enemy ranged minions so that they will shoot you instead of your minion wave. This can be even more important when enemy minions are about to attack your structures. Minions deal bonus damage to structures, so it can be important to keep aggro on yourself and tank the damage. This is because outside of a few supports, you cannot heal damage on your minions, and apart from MULE on Abathur it is impossible to heal structures, making that damage permanent. Damage to your health pool, however, can be easily healed.
The off-lane logic changes slightly when you are playing a global in the off-lane. Global heroes are ones that can cross the map very quickly, such as Dehaka and Falstad. This means that you can stay in the off-lane for a very long time before having to join your team, as you can join on a moment's notice. In short, this means that you should continue to pressure the off-lane so long as your team does not need you, and you can get a free experience and structure advantage from your presence there. Alternatively, you can also create a 5v4 very easily by globaling to the 4-man, which will let your team easily accomplish something, such as stealing a mercenary camp or forcing an advantageous fight.
The classic question: should you defend a lane from mercenaries pushing, or should you go to the objective? As an off-laner your mindset should always be “what will yield my team the most XP relative to my opponent's XP?” Leaving mercs pushing in a lane will result in the enemy team getting structure damage in, resulting in them getting more XP relative to you. But the answer to this is map, comp, and overall very situationally dependent (as most decisions in HotS are). You should keep the following factors in mind:
Are you a global? - If you're playing a global hero, and you will have your global available in time, then you should almost always clear the lane as there is no real time lost since you can show up to the fight instantly.
How long does the objective last? - Can your team stall the objective without getting demolished in a 4v5? Is it an objective such as Shrines or Volskaya where it takes a significant amount of time to secure the objective, regardless? Can you attempt to fight halfway through the objective being done to try to secure it? The answers here will influence your decision to clear or rotate.
How strong is the objective? - Late game objective will usually yield a keep or more, and that will usually be more than a mercenary camp will be able to push through (with the possible exception of the shaman camp on BoE and Shrines). Remember that objectives scale well, and late game objectives become much more important to contest than early game ones. You will have to consider other things too, such as how much structure damage is already in the lane the mercs are in, as well as the lane the objective will be pushing. If you will lose a keep to the objective almost guaranteed, but only lose a fort and a keep wall to mercs, then your decision should be made.
Ganks and Vision
An oft forgotten thing in solo queue, vision is extremely important for any off-laner. The reason is simple: dreaded tourism to your lane. Knowing who is showing on the enemy team at any point is crucial for an off-laner to be aware of. During any game, you should keep track of who can kill you on the enemy team. Do they have a Genji? A Maiev? Do they have as strong ganking tank like E.T.C., Diablo, or Anub’arak? Do you have the means to escape from said ganks? Make a mental list of who can kill you, then when they go missing from the map make sure you back up from your lane to a point of safety. A good rule for someone learning how to off-lane is this: assume whoever is missing on the enemy team is coming to kill you. And in many cases, they are.
Braxis Holdout and Dragon Shire: Point Control
The off-lane changes significantly on Braxis Holdout and Dragon Shire because not only do you have to get XP, you also have to win a point. This means that you often will be in a real 1v1 solo lane and trading damage with your opponent. There are many heroes that excel at 1v1ing but lack in waveclear, and so it is common that, if played correctly, one hero will win the point, and the other win the lane via superior waveclear. Understanding what your matchup is like is crucial to playing on these maps well as an offlaner.
If you have better clear, but are worse at dueling you should aggressively clear the lane to push your wave up, then attempt to get on point. If your lane opponent responds to you on point, they will lose soak in their lane and take some structure damage, and if they clear your wave, then you can maintain control of the point for a short time. Try not to fight them head on if you can avoid it, unless you desperately need control of the point for a few more seconds.
If you have worse clear but better dueling, you should attempt to trade into (fight) your opponent as much as possible. Often times at lower levels people will gladly try to 1v1 you for no real reason. You can use the threat of damage to bully your opponent off of soak by preventing them from stepping up to the lane. This is even more effective when you freeze the lane on your side of the map which forces them to overextend even further to reach the wave.Getting favorable damage trades onto them can force them out of lane or even kill them.
Special Note: On Braxis in particular, it is actually very important to maintain control of the globe generators if you can. A regen globe is 9% of your health and 7% of your mana. It is actually a very significant source of sustain.
If you have questions about off-laning, or about anything the game, really, I highly recommend CavalierGuest's discord, The Nexus Schoolhouse where you can ask anything about HotS and a highly trained team of sloths will get back to you.
Credit for the information in this article goes to the following sloths: CavalierGuest, Epixors, and Froge. Also a special thanks to my editor, Lord 'Boo, for helping with this! Thank you all so much in helping me make this! I could not have done it without you guys.