Unkillable monster due to pilfering bug

I have managed to make a 4300 divination card boss with pilfering scarab. Its IMPOSSIBLE to kill, it seems like there is some rounding error with the damage, i have a 100M dps build and i cant do ANY damage. I brought several uber boss carry with 150million dps, same, no damage. We cant even LEECH mana of it because we are doing ZERO damage. The map contained no mod related to the boss tankiness, only pilfering. There should be a hard cap to prevent invincibility

Same, can confirm it breaks at exactly 4000 cards. 20,000% toughness makes the boss invulnerable.

I am having the same issue. Got over 5k cards on a boss who was invincible. Next map had about 4.3k cards and the boss still took no damage. To give context this is with a 1.7 billion DPS Penance brand build that deletes Ubers and wisped titanic unique bosses in a fraction of a second. I am not sure if this is intended or if it is a bug.

Pretty sure that that's intended, you can read about it here: https://www.poewiki.net/wiki/Divination_Scarab_of_Pilfering

Basically, never get a boss above 3980 cards. Try to do it in a map where you can quickly get to the boss to check the number, like Dunes.