Why don't astro cards stack?

[HyoMinPark]

Oh and as it seems I can post again:

See my long post above. Diurnal AST HoTs do not stack.

Diurnal AST HoTs do not stack the same way WHM HoTs do. They never have. That's why you don't see two ASTs both in Diurnal Sect for things - one is always Diurnal and the other is always Nocturnal. And that's not because of a "shields are needed" thing either (shields aren't needed for anything other than high-tier Savage and Ultimate); it's because AST regens do not stack with one another. CU’s HoT also does not stack if you have two ASTs. None of their buffs stack, except for maybe Synastry (and I wouldn’t be surprised if it didn’t).

I literally just tested this with a friend—we were both Diurnal AST in a party and our regens (both Aspected Helios and Aspected Benefic) overwrote one another’s. They do not stack.

If you think I'm wrong, feel free to test it as well.