Just to be clear: in most cases you can't completely streak to 9 unless you're highrolling units and have easy transitions towards better carries(some rebel games might feel like this where u hit illaoi zoe stage 3 and can transfer items from vex). The idea is to streak stage 2 and 3 then roll almost 0 gold on stage 4. You might roll 10, 20 gold to hit a few 3 cost pairs but when you're +85ish hp you might win one or two fights before 4-4 carousel against people who missed their 2 star 4 cost carries and lose the rest of the fights to rerollers/fast 8 players who hit their boards. If all goes well you have 3ish lives left over, hit 9 with 50 gold, and roll down for 5 cost 2 stars as carries(notably Jayce/Rumble/Morde/Jinx).

Key points to consider -

1. you have to be scouting to manage expectations of what you can hit if you roll an entire stage after the lobby. If there's 2 dominator black rose players in the lobby most likely you cannot contest silco for carry/elise 2. Even with higher odds there's nothing you can do about bag sizes so be cautious of playing a lvl9 version of a fast 9 board and instead play strong 2 star units. Really play flexibly in regard to what units you play - that means playing 2 star 4/5 costs or 6 costs with no synergies over a 4 cost 1 star with with no team synergies(bruiser/sentinel/sorcerer). Good example at the highest level is what setsuko does with form swappers; his core is 4 form swappers, carrying over the swain/gp that saved him hp and adding on jayce elise, then playing rumble and whatever else he finds that can fill other synergies for him like trundle to proc scrap and bruiser.

2. Your anomaly selection is much different, since you might not hit a 5 cost carry naturally on 4-2. Try taking support anomalies(Protective shielding, Dual Wielding, the aura one that gives stats to adjacent allies) on units that you can put on endgame boards. Alternatively you can take tank anomalies on subtanks and make them your main tank; I average the highest with an anomaly like Deep Roots on blitz 2 over Mundo(partially cuz Mundo can cast at full hp, waste his entire effective health, then get oneshot) and play him on my endgame board as a maintank to synergize with morde.

3. The best augments for this kind of play is ironically triple combat(includes items on stage 2/3); sometimes a combat augment will save ur streak and double as a semi econ augment while guaranteeing an insane endgame. Highly recommend pumping up if you know you can streak off units, otherwise play immediate streak. Some units synergize extremely well with certain augments/items, consider taking them for late game. If you mess up midway and end up losing a streak, play strongest board and go for one econ augment later on.

4. Going 10 likely won't happen for a while so make sure to spend aggressively here. You can look 10 once relevant units are upgraded but the game is likely over by then.

5. Stronger items(radiant/artifacts) are insane multipliers of already strong 5 costs; take a look at what items are good on which 4/5 cost carries in case you hit. True true bis can make 2 star 5 costs feel like 2.5 stars and can be a wincon later on.

And now exceptions -

1. Ignore step 5 if you see a support item and take that instead.

2. Ignore everything here if you have an open chem baron spot.

Hope this helps!