What is freezing and how do I do it?

I made a post a while ago called "Tips for Learning to CS" (here), and it ended up getting a lot of views after being linked from reddit, so I was reading over it, and I realized that while I tell you to freeze, I don't explain exactly what that is.

So: What is freezing, and how do I do it?

Freezing is the act of keeping the minion "line of scrimmage" in exactly the same place for as long as possible.  You can do this to deny your enemies CS or to keep yourself in a safe position so you can get all of your lasthits without fear of ganks.  This sounds easy enough, but actually doing it can be pretty tricky.  Your goal is to make sure that their wave is pushing in on yours constantly but you don't let it actually advance forward ever.  The rest of this article will explain how to do that.

The first thing you need to do is make sure that you never have more creeps currently fighting than the enemy does.  There are a few sub-criteria here:

• Make sure your creeps aren't arriving before the enemy creeps, unless there are so many surplus enemy creeps that it doesn't matter.
• Make sure that you don't have more ranged creeps than they do.
• Make sure that you don't have a cannon creep when they don't.

The first point needs some clarification.  Some places are easier to freeze than others.  The easiest places to freeze are where their wave will arrive about 1-2 seconds before yours, so just in front of their tower.  Anywhere in between the midway point of the lane and the point at which your creeps are just out of range of their tower is fine, though.  If you have enough lifesteal that you can tank a lot of creeps in between waves, then you can let a really big stack accumulate basically wherever you want and let it run through your waves.

Because ranged creeps do more DPS than melee creeps, and cannon creeps are very difficult to kill, you need to make sure that your stack doesn't exceed the enemy stack in either of these categories.

The second thing is to be careful about the amount that you yourself are pushing the lane.  Again, there are two things you need to do:

• Don't do too much damage
• Don't tank too much damage

Both dealing damage to their creeps and tanking damage that should be dealt to your creeps push the lane.  Dealing too much damage is like adding creeps to your stack, and tanking damage is like subtracting creeps from their stack.  (Obviously it's fine to tank damage from their side once all of your creeps are dead.)

How can you do this?  First, time your last-hits carefully.  Ideally, your last-hit projectile will hit the creep the split-second before a projectile from one of your creeps would have killed it anyway.  The important part is that the killing projectile was already in the air, because in that case you're not actually decreasing the number of attacks that your wave threw against them by taking the lasthit.  Sometimes this isn't possible, but if it is then you should.  It takes a lot of practice to be able to do this reliably without missing too much CS.

Second, pay attention to when your creeps are dying, and when one is about to be killed, make sure you're NOT the closest target to any of the enemy creeps that were targeting it (unless you're in a bush).  You can do this by always being positioned behind your creeps, it's just that sometimes you won't want to be positioned that passively, for example if you and your support are able to zone together but your support is vulnerable to getting jumped on if you're out of engage range.

Next, pull the wave to a better position when possible.  This can only be done when their creeps kill an entire wave of your creeps before your next wave arrives.  It's easier to pull melee creeps than to pull ranged creeps.  What you do is you aggro the enemy creeps to you and then walk in the direction that you want to pull the wave (towards the enemy half of the map).  As your creeps approach, walk to a position so that you'll be able to deaggro the enemy creeps immediately; having a nearby bush is good for this.

Finally, give up important lasthits when your freeze is extremely delicate.  If you can just barely maintain the freeze, and you won't be able to sync up a perfect lasthit against one of their creeps (particularly the cannon creep), don't lasthit that creep.  Usually, maintaining a freeze is more important than that 40 gold.