Explain the Amazon Decoy ability to me.

Here I am, doing my Hell playthrough and I'm using the

Decoy to disrupt enemy groups and make large mobs of enemies manageable. While doing

Nihlathak's lair, I've noticed that sometimes, the

Decoy will get popped instantly, while sometimes it's just straight up immortal and will last the full duration every single time.

What causes this behaviour? I assume this isn't how the spell is meant to work and it seems to change every time I TP back to town or switch floors. Is there a way to trigger this behaviour consistently?

It's a new D2R bug:

I believe this part is relevant:

Issue 1:

Skill Bonuses for the

Decoy apply and “stack” after every skill cast , resulting in ever-increasing/overflowing HP and Resistance values.

This will cause

Decoy to feel either indestructible or die in 1-hit depending on the levels and clicks involved (Overflow/Rollover).

Dear Blizzard please never fix this bug I don't know how I'm going to make it through Hell otherwise