Cryogenic Longbow

Weapon

Very Rare Wisdom Based Spellcasting Requires Attunement

Ammo(Arrow), Two-Handed, Occult, Runic

When used as a Spellcasting focus, you gain +4 to your Spell Attack Modifier and Spell Save DC.

Complicated Properties

Occult. You can use Wisdom as the modifier for this weapon.

Runic. You can use this item as a Spellcasting focus.

Spell Boon

Arctic Blast. you can cast a variant of Ice Beam at 7th-level without expending a spell slot.

This variant differs in that, the range becomes 150ft, and any creature within 5ft of the target is also slowed.

Rules for Catalyst Boon's can be found here: Spellcasting Catalyst