Frozen Dagger

Alter: Attacks made with this dagger deal cold damage instead of piercing. If you roll a 20 on an attack roll made with this dagger, the target must succeed on a DC 12 Constitution saving throw or be paralyzed until the end of its next turn, frozen in place and unable to move. If it succeeds, its movements speed is halved until the end of its next turn instead.

Attunement: yes
Rarity: Uncommon
Type: Dagger
Cost: 170gp

Griffons Saddlebag, Vol 1