Necromancer Card card_crypt_old

What it is for

Card: fits into Right hand gear that has a free slot.

Chance to cast a Shadow strike on attack 5%. Damage against bosses +15%.

Weighs 2 of your carry capacity — and weight is what stops drops once the bag fills up.

The best source is Necromancer, at 0.020% per kill. You can farm it at Old Crypt.