Somehow, my post got thrown in the wrong forum.

Unlike every other status effect and artifact I am aware of, Quantum Flare seems to stack with itself. Is this intentional?

Yes. Intentional.

Really more of a question for the designer of the game, but whatever. It should be fixed to work like everything else, or at the very least, a note added to its description so as to inform people of its exceptional function.

There are others that do this also. EMP spheres come to mind.

In my experience, EMP Spheres say 'Another similar effect is already in place' if you try to use multiples. Unless it's different for players than for NPCs.

It is.

That would be my confusion then - so I can just use 10 EMP spheres on someone to completely negate their defenses?

Not quite. The sacking is multiplicative... First one reduces defense to 90%, second is 10% of that or 9% of original. Third would be -10% of 81% or 8% leaving 73% of the original stat... and so on and so forth

Right, but 100% - 10% - 9% -8.1% -7.3% - 6.6%... et cetera.

Even accounting for diminishing returns, that still takes defense down to about a third. So it's not complete negation, but it is kind of overkill.

It stacks until you get 37 pieces of flare

Guess that explains why I got hit with 7 flares in a row in a 2 minute period.. and then still not hacked or disabled.. It was just weird..