Say I completely surround a figure in barrier then use and hit with Larfreeze's quake, how many damage does the figure take if he doesnt have any damage reduction?

It would just be the three. It is one attack, and you get to pick what square the knockback hits from.

2 damage. Larfleeze is only using Quake from every square of blocking terrain, not FOR every square of blocking terrain.

it would be 3, because he is knocked back into the other barrier

Knockback damage is NOT added with damage from the attack.

Quakes deals 2 damage and causes knock back, which would then deal 1 additional damage for being knocked into the barrier. But theses are two separate instances of damage, so even if the character doesn't have damage reducers when hit by the attack, that damage might knock him onto a click with damage reducers, which WOULD work agaisnt the knock back damage.

This works with characters with powers that stop turning the dial, too.
Larfleeze hits a white lantern character, for example, and the 2 damage from the quake is enough to get to the Live! click that stops turning the dial. But then the knockback damage kicks in, and will deal 1 more damage, getting past the Live! click.

That's why it matters that it's 2 damage, then 1 damage, not 3 damage at once.

I'm gonna piggyback this one.

How is knockback direction determined? Does the Larfleeze player choose knockback direction from all possible knockback directions for each target? Or is each character explicitly knocked away from Larfleeze's current board position?

Larfleeze picks which square he knocks the opposing character away from. It's under "multibase characters" in the rules.

I question the valudity of this assumption, because:

However, assuming your assumption was correct and Larfleeze counts as a multibase character, those rules can be found here:

Also, to quote the power in question:

So, "when attacking" pick a square. Not exactly sure "when" during the attack you pick it, just be sure you do.

Also, oddly enough, if it matters for some reason, none of the blocking should block line of fire to Larfleeze during the attack because he is attacking as if he occupied multiple squares, making the blocking terrain squares he occupies, and squares a multibase character occupies do not block line of fire to other squares that multibase occupies.

False. Knockback direction is always determined from the character making the attack. It doesn't matter which square of blocking terrain larfleeze chose.

You claim knock back is determined from the square Larfleeze occupies. Larfleeze's power says he occupies the blocking terrain. So do you knockback the opposing character based on the square he occupies, or another square he occupies?

GREED: BARRICADING: Larfleeze can use Barrier and Plasticity. When Larfleeze uses Barrier, after actions resolve, he can use Quake as a free action as if he occupied all blocking terrain markers placed by friendly characters with the Orange Lantern Corps keyword

Larfleeze does not occupies any square of blocking terrain (that would be illegal). Larfleeze attacks as if he occupies any of those squares, but he occupies his square. That is from where the knockback is determined.

I do not think you are using that phrase correctly.

I agree with DonJoaquin. The phrase 'as if' does not change where he is. If you want to prob the attack you must still draw lof to Larfleeze, not the square he is attacking from.

This has already been ruled on by the rules team. You choose one square of Blocking Terrain that Larfleeze is attacking from for each character and that character is only knocked back from that square.

Did they justify that by stating Larfleeze counts as a multibase character? Or was this an errata/clarification specific to Larfleeze?