When Should You Splitpush? Q & A
This question has been posted in General
It's important to understand that if the enemy is pushing your inhibitor or has unstoppable momentum when 5v4 then you shouldn't split push. At that point you need to help your team push them off the towers otherwise you will lose valuable objectives far too quickly. If you have teleport and the enemy sends 2 or more people to stop you then you can teleport back to your team and help them kill the enemies who stayed behind. You can also teleport back to base before the enemy takes anything and defend it if the enemy is pushing too aggressively for your team to defend.
If your team is ahead then all you have to do is push out all 3 lanes. Other than that your team just stays together and takes objectives. The enemy may try to beat you by split pushing if this happens and in that case you just have to force push 1 lane and take as much as you can to punish them for it. Sometimes sending a strong duelist champion to kill the enemy split pusher helps.
Also if you are the strongest person on your team then you should be grouping with your team. You need to carry your team in fights if you have all the gold because either you took the kills or your team gave them to you and designated you as the person to carry them. Regardless, you have the team's wealth and need to keep your team alive with it. Hoarding all the kills and split pushing is how many people lose games.
Also all of this is assuming you're playing a champion that can actually split push or have someone on your team who can. Champions that can generally 1v1 or 1v2 basically anyone on enemy team and have great escape and wave clear make good split pushers.
- Your team's teamfight potential. If your team has better teamfight champions than your enemy, you might want to group up to secure a straightforward teamfight win. You should also take in account who's fed, who's behind, who sucks and who plays really well. "Good teamfight champions" are generally champions with lots of area of effect (AoE) abilities (like Amumu, Brand, Sivir, Malphite).
- Your champions' splitpush potential. If you're going to splitpush, you better have some champion that can do it well. Good splitpush champions have mobility, good turret damage, good waveclearing and/or good dueling potential (so that the enemy can't just send one member to get you). Also having Teleport is often necessary. Notice that most of this stuff can be somewhat enhanced with your build. A Zz'Rot Portal will increase the turret damage of any tank; a Tiamat upgrade will give you good waveclearing; a Dead Man's Plate will increase your mobility; etc. You can preemptively buy a splitpush build if you suspect you might be the one to do it.
- Your team's 4v5 performance. You won't be able to splitpush if the enemy team has great engage (like an Amumu or a Malphite) and your team lacks some form of disengage. On the contraire, if your team has good disengage tools ( Lee Sin's ult, Tristana's ult, a Janna) you might have a better chance to win the trade by splitpushing.
- The moment-to-moment state of the game. You might have all of the above on check, but if the enemy is currently taking baron while your lanes are pushed, you shouldn't splitpush. You have to check, whenever you're pushing a wave, if the situation is appropriate for a splitpush. Do you have Teleport available? Do you see at least 4 of the enemy champions far away in the other side of the map? Will you be able to take down a turret then escape? Would it be worth it to take down a turret then die (this one is almost always a no)? You'll have to develop a gut feeling after some games of learning, but the only way to do it is trying and failing a couple of times.
Hope the list helped. Most of the stuff needs to be checked on a case-by-case basis, so feel free to ask. If you're asking about a particular champion, you might want to ask within a guide that explains late game for that champion, but if you want to know about a whole team you'll have a best chance doing a post (not just a question in Q&A) with both teamcomps and asking for help in the forums.