League of Legends
When playing bottom lane you need to be very aware of when you have an advantage on your opponents. A 2v2 makes it inherently easier to get the most out of being ahead.
In this article we will look at four clearly distinct types of advantages in the bottom lane 2v2: summoner spell advantage, health advantage, gold advantage and item advantage. Level advantage has already been covered in a previous article ("Planning the Lane Phase").
Summoner spell advantage is an obvious one, you have this advantage when your summoners are up and your enemies aren't. How do you press a summoner spell advantage? Easy, by fighting. Having summoners on your opponents in most cases guarantees you will win a 2v2, either because you have better combat tools (heal, exhaust, ignite) or because you can Flash on them and CC them for a great engage they can't Flash out of. Basically, if you have a summoner advantage on your opponent, play aggressive and look for fights. Being up a flash or a heal makes for super easy ganks from your jungler too, so let him know.
You have a health advantage when, well, you have more health than your opponents. This is more complex than it seems. You have to consider whether your health is on the ADC or on the support, e.g. Graves Leona, if Graves has 300 more HP than their ADC but Leona is at 100 HP and their support is full health, you probably can't fight as you need Leona to tank. On the other hand, if Leona is full, and the other 3 laners are at half health, you can easily burst the enemy down.
Another thing to consider: is your health advantage immediate or over time? If you have more health than your opponent right now, it's immediate. When both teams have the same health, the health advantage over time is gained by having more lifesteal, more potions, or more mana on your sustain support. In these cases you should wait until you turn these resources into actual health before pressing the advantage further.
Immediate health advantage is, again, abused by being aggressive. If you walk up to someone you have a health advantage on, they will not be able to take the all in and you can zone them and push them out of lane. Over time health advantage is abused by taking trades: a 400 damage for 400 damage trade becomes much more attractive when you know you can regain that health in 10 or 15 seconds and your opponent can't. Pay attention to matchups when considering this and be careful of being all inned by laners that are stronger than you right now.
Item advantage and gold advantage naturally come hand in hand. More gold equals more items, which equals more combat stats that lead to winning fights. Seems easy enough, right?
Remember that gold advantage can only be turned into item advantage when you go back to base. A common mistake in lower ELO is not backing after getting an early kill. Let's say you get a kill at 4 minutes and have 750 gold after pushing the wave. If you stay, the other ADC will come back with full health and a second doran and you will probably lose the fight. Usually the person who has one more back on the other will have more items and health and will win fights. If you are going to be greedy and stay waiting for pickaxe you need to make sure you don't get engaged on and die or you will have wasted your advantage. You can try to look for trades, as they will be essentially free damage since you are looking to go to base soon anyways. A smart person doesn't fight a man who has an extra b on him, rather pokes him and gets free damage before his own b. Gold advantage has different impact at different points in the game. If you have a 300 gold advantage and you back at 1200g, the other person will have 900 and the only item you will have on them are boots if you get that on top of your pickaxe. You should try to stretch out the lane to where you have 1550g and force the recalls then, as there you will have a BF sword versus a pickaxe. Basically, having a gold advantage can be turned into a big item advantage if you time your recalls correctly. Aim to recall as soon as you have gold to finish an item, which will hopefully be before your opponent has time to do the same. As an extra note, for triforce ADCs your big spikes are phage+sheen, and the full triforce. This is 2500g and 3700g so be careful of BF sword ADCs that will try to press their advantage between 1550g and 2500g.
In closing, health advantage, summoner spell advantage and item advantage are all pressed by playing aggressively. They all allow you to either win a fight outright or let you take the winning fight more easily. Gold advantage does not give combat prowess, and should be turned into strong item advantage by correctly recalling when you have sufficient gold to reach your big items, and your opponent doesn't.