I get the 6 cards to guard when you have two RGs attack first, and then breakride VG attack to swap those two RGs (or two Purple Trapezists) for another two unboosted attacks/one full attack/two full attacks.
Just pointing out that unless you have Trapezist, that's not the optimal attack pattern. Even with Trapezist, it's rarely the best attack pattern.
The best attack pattern in general (meaning there are exceptions) is:
front RG (at interceptor or VG if it's a 11~12k) > front RG (at interceptor or VG if it's a 11~12k) > VG > full RG column > full RG column
Do note, the initial front row RG attacks should prioritize interceptors over VGs, because if they NG the attack to the VG and checks a trigger, you're screwed.
And the attack pattern is because interceptors are still worth as 5k shields, and generally it's very bad to first swing with higher numbered columns and then later swing with lower number columns. This is because if you swing with full columns first and leave later attacks on weaker attacks, then when you check a trigger, that trigger won't force out more cards. Passing +5k and crit to a 16k column forces 1 additional card, while passing +5k and crit to a 11k column doesn't because it can be guarded by a 10k shield.
Killing interceptors also have the added bonus of assuring that 5k shield's quality and some information about their hand; if they want to guard for that RG, chances are they're low on attackers or the quality of attackers, an information that you wouldn't have known otherwise.
And lastly, the most common attack pattern for me with the 3/3/2 BR turn is, assuming that I BR Luquier Reverse over Eva:
first form a 21/21/16 field by locking VG booster and calling a G1 booster from the soul, not attacker, and apply the +5k to that called unit. This gives you a 12k booster, which will give you a better attack pattern than calling a 14~17k front row attackers 99% of the time.
This setup allows you to swing for the following pattern:
9k > 9k > 21k(VG) > 16k > 21k = 7 cards to guard
and if you checked a trigger, you are essentially swinging for
9k > 9k > 21k(VG) > 21k > 21k = 8 cards to guard, without giving them a chance to damage check a trigger first before guarding the 21k attacks unless they NG your VG attack first.
Also, could you give me a step-by-step example of how Eva would give additional attacks with the help of Marcia or Ana?
It's not that Eva allows them to guarantee addition attacks, but that they apply the pressure of potential additional attacks if they successfully land a hit and you didn't damage check a trigger. Meaning your opponent is gambling on getting a trigger on his damage check to have you not perform additional attacks. This is a good thing because it does apply that pressure and tempt them to guard your potentially 21k RG attack that should only have been worth 1 damage, but 2 cards if guarded.