League-of-legends – When is it an appropriate time to gank a lane as a jungler

Roaming has become a popular addition to the metagame strategy, wherein one player does not lane nor jungle, but rather simply moves through the jungle/river to initiate ganks on lanes from level 1 and onward, until the teamfight portion of the game begins.

A roamer essentially guarantees that you're either running a solo lane, or two solo lanes if you have a roamer and a jungler. I've also seen a double roamer game played, though this tends to be less effective as enemies who are wise start playing defensively and reduce the effectiveness of your roamers, which put them behind in both CS and levels.

The qualities of a roamer can vary, but the general requirements are that they are mobile, can do burst damage, and have a strong stun or position altering (push, throw, etc.) ability. Taric, Evelynn and Alistar are all very popular choices for roaming. I've also seen Sion and Blitz play roaming effectively, but they were both out of a lack of a jungle spot on the team and normally suit better in a lane.

This strategy is similar to the "double jungle" mindset in that you get three solo lanes, with the exception that there is extra pressure on getting early kills to succeed. A definite risk vs. reward tossup, as successful roamers will quickly catapult your laners ahead in level / CS as well as demoralize your opponents, but unsuccessful roamers will fall just as far behind due to the lack of their presence in the laning phase.

Left to their devices, minions will eventually be able to push even to the base turrets. Which side accomplishes this, however, is random, and it's basically based on how attacks are being distributed.

Minion targetting works on the following priority scheme, brought to you by the League of Legends Wiki:

1. An enemy champion who is attacking an allied champion.
2. An enemy minion who is attacking an allied champion.
3. An enemy minion who is attacking an allied minion.
4. An enemy turret who is attacking an allied minion.
5. An enemy champion who is attacking an allied minion. (Tangential, but this lower priority is why they don't pay attention to you when they're bashing your towers)
6. The closest enemy minion.
7. The closest enemy champion.

Now, when waves engage each other, there are a lot of minions attacking a lot of minions. So each minion picks some sort of target, but it is mostly random within that scope. So blue's caster minions could all be focusing down one purple melee minion, while purple's caster minions are split with two on one blue caster and one on a blue melee. The focus fire will reduce the enemy numbers, in turn resulting in one side having an advantage. But because how the focus fire is attributed is random (both mechanically and because the actual positioning of the minions can differ greatly as a result), the side that gets an advantage is completely random.

This compounds due to two major factors as the game progresses.

• Once siege minions enter the fray, they both deal more damage and take substantially more damage. They can prolong battles long enough for secondary and tertiary minion waves to support them, which can greatly turn the tide of battle even more depending again on how focus fire is attributed.
• If a small minion wave pushes far enough, then when the next minion wave comes in the enemy will have a shorter travel time before its support shows up. With the aforementioned siege minion stalling, the end result is that one side builds up a massive force that just has to deal with the opposing side one wave at a time.

As such, eventually, they amass enough force to push down full towers, much harder than the defense can manage. Even when the defense can stall, the sheer numbers built up from the initial push can have a devastating advantage... at least until their focusing messes up and the force builds up in the opposite side.