Now let's play the numbers game with the dice. I will jump right into, your chances for a hit is 37.5% , critical is 12.5%, ok with that in mind you now have 50% chance of a hit sounds good right? Now add the chance of getting a focus roll that's 25%. Blank rolls are 25%( I like that number.) With those numbers the no brainer here is to focus your attack that's a big 75% chance of a hit (criticals are just a bonus). Ok let that set in for a minute...

Time for the defense side, chances of a evade is 37.5% (not good at all). Getting a blank is also 37.5%,and rolling a focus is 25%. Now with that if you saved your focus for defense you have a 62.5% chance of a full dodge.

That's all I have for now I do apologize if this subject has been explained before.

For attack, technically TL is slightly better. They both give the same 75% chance to hit, but the chance for a crit is increased with TL and is not with Focus. If you're trying to figure out whether it is better to spend your focus on attack or defense, math cannot answer that alone. You need to also know how many ships are going to attack you, and with how many dice (for example, if you're out of everyone's arc, it's pointless to not spend your focus on your attack), as well as how many dice you're rolling for each defense and your attack.

If you're attacking a TIE fighter from an X wing and rolled blank hit focus... spending the focus is unlikely to do anything, especially if you don't have anyone else to attack that TIE. Perhaps you know that another ship is going to attack as well, so you want to strip him of his token, in which case it might be worth it to spend your token to force him to spend his evade/focus.

As I said, it's very situational as to how to maximize the focus. Perhaps you have a stealth device and therefore you really want to keep it for defense. These are all variables that you have to decide on the fly and there will never be a mathematical prove out as to what is better. I'm sure there's going to be a time where math says that it's best to wait for defense, but you know that if you spend it, you have a chance of killing that ship right here and now. That chance might be worth it if it means it can't shoot back.

To be honest, this is part of what makes focus the best general-purpose option for lower skill pilots - by the time you get to shoot, anyone who's going to fire back at you has already done so; so you know you don't need your focus token defensively anymore.

But yeah...especially in a head-to-head pass, whether to use a focus token or not on a target before it shoots is a big gamble (unless you've got two or more focus hits riding on it, where it becomes more of a no-brainer).

I have a question related to this: mathematically, what's better for attacking for an x-wing: Focus or the extra attach die from Expose?

Another question: Again for an x-wing - what's better defence: focus or R2-F2's extra agility?

I'm asking purely mathematically: for the first question you only care about attack and for the second only about defence.

Let's see if I can work this out myself:

Starting with defence, if you have two dice that's an average of 0.75 evades. If you had focus that would be 1.25. If you had an extra die instead of the focus that would be 1.125, so focus is better, is that right? With a steal device that's 1.5 with R2-F2, or 1.875 with focus, so R2-F2 is only worth having if you get a focus from someone else, right?

For attack, focus would give you 2.25 (3 at range one) while expose would give you 2 (2.5 at range 1) so again,expose is only worth having if you get a focus some other way.

Does that sound about right?

For attack - focus (better chance to hit compared to adding a fourth die without the option to flip those focus symbols into hits)

For defence - R2-F2 (because you will likely be attacked more than once in a round so you get that bonus multiple times and also going from 2 to 3 is a bigger deal than going from 3 to 4)

Mathematically - as a single action, Focus is better than Expose for an X wing. When you get a second action, Expose is marginally better. When you get three actions, its quite a bit better. But none of this is counting the downside of -1 agility.

As for Focus / R2-F2, the answer is - it depends. Rolling two dice with a Focus nets you 1.25 evades. Rolling three dice without a Focus nets you 1.13 evades. But... you only have the focus for one roll and you can be attacked multiple times. You keep that extra agility for every attack. As such, after two attacks, you've rolled 1.25 + .75 = 2.00 evades with the focus action, and 1.13 + 1.13 = 2.26 evades with the R2-F2 action. As you can see, R2-F2 gets better the more ships that are attacking.

Personally, I like combining R2-F2, Stealth, and Luke. This gives you 4 dice (excluding range/obstacle bonus dice) and a mini focus. Each turn, you're likely to roll 1.76 evades without using any action. If you actually focus (plenty of ways to get one these days), you can save it for when you need to turn more than 1 focus into an evade, and average 2.50 evades for that turn. Not bad.

*edit for slight error in my spread sheet

For defence - R2-F2 (because you will likely be attacked more than once in a round so you get that bonus multiple times and also going from 2 to 3 is a bigger deal than going from 3 to 4)

But... you only have the focus for one roll and you can be attacked multiple times.

Oh yeah, I was forgetting that. Particularly relevant as I was thinking about Biggsy!