After digging into things for awhile, I believe I've determined the following: * Around UF era, Raid bosses start to get Heroic Strikethrough, a value that will negate all forms of dodge/parry/riposte until you raise either hagi or hdex past some threshold (some multiple of 25), at which point you will start to gain avoidance again (but all the heroics below that threshold are effectively lost). * Each era increases heroic strikethrough numbers (although this can vary between different npcs) requiring an ever increasing amount of hagi or hdex to regain avoidance. * At some point group mobs also gain heroic strikethrough. * At some point, raid NPCs end up gaining so much heroic strikethrough, that you roughly cannot get avoidances back in era. Given all of that, I've surmised that for a raiding tank, picking either hagi or hdex and stacking that is the correct thing to do, until you hit the point where raid NPCs start getting 100% strikethrough, and then at that point you're better off stacking hsta. Assuming all of that is roughly correct, the one thing I haven't been able to find any real information on, is at what point raid NPCs start gaining so much heroic strikethrough that it's better to switch from stacking hagi to stacking hsta. Does anyone happen to know what era that is?