This is the basin
This is how the pistons are set up
This is how they're wired up, the bottom tier is controlled by wireless redstone, the opposite sides are paired up, the higher tiers use an inverted signal from the lower ones.
This flipper controls the bottom tiers.
This is the weakening system, it's two trapdoors and a piston suffocator
This is the circuit which controlls the trapdoors and pison. The sequencer is set to 6 seconds, the piston timer is 3, the trapdoor repeaters are both on in the fourth position.
The leftmost wire controls the bottom trapdoor, the second controls the upper one, the right wire controls the suffocation piston
And it works like this: blazes are collected above the upper trapdoor, they're dropped down, suffocated, then dropped down do the kill area. You get so many blazes every second, that you might not kill them all before the next batch arives.