WHAT IS COUNTER-JUNGLING?
Counter-jungling is the act of invading the enemy jungle and killing their minions. Counter-jungling can also consist of ganking the same lanes at the same time as the enemy jungler. This kind of turn around on a gank is specifically known as counter-ganking and can be very demoralizing for the enemy team. How fast you and your opponent clear jungle camps is a huge factor in how well you can counter-jungle.
WHY COUNTER-JUNGLE?
Counter-jungling has several benefits. The first is that you are effectively stealing experience and gold from the enemy jungler. By leaving one of the smaller minions in a camp, you do not allow the respawn timer to start. This means that the enemy jungler must find the camp stolen and clear it himself before the respawn timer even starts. They also waste time traveling to that camp and realizing that they have been counter-jungled, meanwhile you are onto the next creep camp or ganking a lane. If done frequently enough, the enemy jungler will begin to lose considerable amounts of experience and gold, as well as grow frustrated. If the enemy jungler is letting their middle lane take the wraiths, then this could even set back and frustrate their middle lane.
WHEN DO I COUNTER-JUNGLE?
First of all, whenever you counter-jungle, your team should be aware that you are invading enemy territory. If your team is not warned before hand and you are caught, you can easily be trapped in by their jungler and adjacent lanes. Always make sure they know where you are and that they will come to aid you if you need assistance. It is almost always safe to invade the enemy jungle when the enemy jungler is ganking a lane. If the gank is too far away or you are too late to counter-gank, then invade the enemy's jungle and take what you can. Warding is another good way to know where the enemy jungler is, even when he is not ganking lanes. This will allow your lanes to know when it is safe to push and when they should play more defensive. It will also allow you to counter-jungle that much harder. For more experience players, try to keep timers on enemy camps. This will allow you to be at the camp seconds before it spawns, while the enemy jungler will only start heading towards the camp once they see the marker on their map re-appear. This allows you to take the camp while they are on their way, letting you get away without being touched.
Very few champions can counter jungle effectively. Things you should look for in a counter jungling champion would be clear speed, damage, and escapes. Junglers such as Lee sin are well equipped for that. His dueling capabilities and buff control is outstanding for a champion. Some other champions thats advatange of their kit are Shyvana, Dr. Mundo, Nunu, Udyr, and Zed.
The key to counter jungling is all about timing and knowledge. If you are looking to just steal a camp and avoid controntation, you should never go into enemy jungle without knowing where the opposition is at. Always remember, your allies will be farther away than your enemies. If you are looking to pick on the enemy jungler, basic time sets are a valuable tool. For example, if the enemy team has a blue orientated jungler like Maokai or Amumu, you can opt to start your own blue, then steal their red right after or start your red, then finish your blue to obtain lvl 3 and invade by going straight to their red and possibly killing them. Which leads to your blue being refreshed and also a possible red buff steal.
A good source of knowledge to take into consideration is whether you and your mid lane have a great 2v2 potential. If you feel as you are better than their Mid/Jungle duo then at 7:15 you can invade onto their starting jungling buff. Possible result would be a kill (s) and a buff steal.
HOW TO AVOID BEING COUNTER-JUNGLED?
When being heavily counter-jungle, wards are your best friend. This will allow you to see them enter your jungle, which with a quick ping can send your entire team showering down towards them. If the enemy team is keeping tight communication, though, that showering down may actually result in a teamfight. If this does not sound good for your team, then resort to counter-counter-jungling. Yes, the name is funny, but it is effective and it will not run the risk of your team losing a fight. This is also one of the safest methods of counter a level one invade, by backing out and then circling to the enemy team's buff.
All you need to know about Counter Jungling | High Elo Jungle Guide League of Legends
