Framework 01
Affinity stack
Choose a hero whose affinity tags you can actually shop for, then buy gear that shares those tags. Sets are tag counts, so every matching piece feeds the same multiplier.
Confirmed basis
Hero affinity +15% is visible on official panels; matching gear gains the bonus. Tag counts appear on the shop and rival screens.
Failure mode
A shop that refuses to offer your tag. Keep one off-tag sustain piece as a hedge.