This comp looks to reroll for Vayne and Leona 3 star. Instead of going for more Forgotten units, this comp focuses more on a traditional team comp with Vayne 3 as the main carry.
Go for this comp if you find lots of early copies of Vayne. You can always transition into a different comp, but if you commit to slow rolling, you should commit all the way.
Don't level up early and save gold to slow roll. Try to use cheap units to jumpstart your economy.
Once you hit 50 gold, begin slow rolling for Vayne 3 and Leona 3. You can skip Leona 3 if you find Vayne very quickly and aren't close.
Begin slow leveling after finding your 3 star units. You can spend most of your gold to hit level 7 if you need to get stronger or have a good unit to put in and want to be more aggressive.
Hit level 8 by 5-1 if you can to complete the comp. You can wait until a few rounds into stage 5 if you are too poor to level up.
When using Vayne, the most important things to pair alongside her are Forgotten and Ranger. Frontline will come with your Forgotten units and Leona while Vayne will be supported by other backline units for more damage.
During this portion of the game, try to have at least 2 Rangers for the attack speed buff. You can place more, but make sure to have your core intact.
The core of the comp is really Vayne, Ryze, Thresh, Leona, and one Ranger. The Forgotten 3 will give Vayne bonus stats and the ranger will give her attack speed. Fill out the rest of your comp with other units you find along the way. Leona can be replaced with any frontline tank like Rell if you are unable to 3 star her.