A major part of what makes Injustice 2 unique among 2D fighting games is the attack string system. Like a 3D fighter, characters have a pile of pre-determined attack strings (for example, light attack, light attack, medium attack) that you have to understand to get the most out of their close combat.
For the sake of clarity we’re going to change up some terminology here. The game menus call what we call attack strings "Combo Attacks". The problem is, when we actually get to real combos as they’re thought of in every other fighting game … that’s going to create some confusion.
Look up the move list and go to "Combo Attacks" for the full list of attack strings. This looks like a lot to remember, but most of the listings you see are branches of just a few different base strings.
How to do them
Once you’ve looked up the string of your choice, simply press the buttons quickly. Timing varies by the string, but most attack strings require the buttons to be pressed extremely quickly.
Attack strings in Injustice 2 have to be input very quickly, usually faster than you can tell if they’re going to hit or not.
This is a very important detail. Some attack strings, particularly those with a big finish, leave the player wide open if they’re blocked. If you mash them out without knowing that they’re going to hit, you may give the other player a chance to land a free combo on you.
Branching strings and mixups
Some strings have branches: that is, a hit can have two or three different follow-ups.
In this example, Catwoman has no less than three different follow-ups to a simple light attack, with each branching off into its own string. One of these is a fast surprise overhead for players who are crouching under her jab, and another ends with a surprise low sweep.
Moves like these are usually unsafe, but because they can catch your opponent off guard, they can be acceptable risks.
Slip moves like this into your attack to catch your opponent off guard, and in turn know what your opponent’s character can do so that you can defend properly.
By the same token, just because a string has three hits doesn’t mean you actually need to use them all. Cutting off your strings early can give your opponent a moment of confusion, as the attack they expected never comes.
Defending attack strings
Generally speaking, don’t try and interrupt your opponent with your own attacks. It’s probably not going to happen, and you’re going to take a counter hit into a combo. Block patiently and only begin your counterattack once the string is over.
The best defense against an opponent’s attack string is actually knowing it yourself. If you know that there’s a surprise overhead hit in a certain string, you can just make sure you’re standing when you see the first few hits of that string come out. Of course, that’s a lot to know, but that’s a reality of high-level play: others will know all about your favorite tricks.