This game needs less % pen and more flat pen

if a person wants to itemize against someone who has a tremendous amount of armor, they should have to make a significant investment in items that grant penetration, not just buy 1 item that costs 2300 gold.

flat armor pen should be much higher across the board and damage should be lower to counterbalance that so that the damage to squishies remains relatively the same. It should take about 2 top tier flat armor pen items to completely penetrate all the armor of a squishy, and from there you can either build more raw damage for doing more damage to squishy targets or a couple more armor pen items for more damage to more durable targets.

A typical build that includes pen would consist of first rushing the first pen item and then not building a second pen item until about 25 minutes into the game when people start to max out on their levels. In order to make it the rush item doesn't waste most of its penetration (you can't penetrate armor that they don't yet have) or overtly punish people for building early armor, it would grant armor penetration that scales with how many levels you have, and would be rather cheap because of that. The other flat pen items would have difficult build paths and be very expensive in order to make it atleast moderately difficult but not impossible to counter a quick armor rush.