I have checked out the odds for the matches today.
Let's say I preferred 2-0 G2 win @1.13, BIG win @1.38 and FaZe win @1.40 the total odd becomes 2.18. However I see quite big risks in such a parlay. For example I don't know if it's worth taking a risk for the G2 match for only 1.13 odd. Maybe they will lose one map surprisingly and everything will end quickly. The BIG option is also a little risky in fact. Because BIG are still in a terrible form. They are a much more qualified team than MIBR of course. MIBR newly played against top tier teams and lost both matches. However they won a map against FaZe and maybe they might be able to do even better against BIG. The only very reliable option seems to be FaZe in this.
BIG's form in the last nine matches is really horrible that's why I don't trust them fully even against MIBR: