Pick of Ice Breaking

The metal head of this war pick is covered in tiny arcane runes. You gain a +1 bonus to attack and damage rolls made with this magic weapon. The bonus increases to +3 when you use the war pick to attack a construct, elemental, fey, or other creature made almost entirely of ice or snow. When you roll a 20 on an attack roll made with this weapon against such a creature, the target takes an extra 2d8 piercing damage. When you hit an object made of ice or snow with this weapon, the object doesn't have a damage threshold when determining the damage you deal to it with this weapon.