Blood Cleaver

Weapon (battle axe, greataxe), uncommon   This axe, created by the war-smiths of Yerna, is made to slay both the beasts and men that have lost their sanity within the cursed continent. In its regular form this weapon is a battleaxe, dealing 1d8 slashing damage, and it gains a +1 bonus to damage rolls against humanoids.   As a bonus action, you can change the weapon’s form and extend it, transforming it into a greataxe, which requires both hands to wield. If you are wielding a shield in your hand when you transform the weapon, you can stow it as part of the same bonus action. In that form the axe deals 1d12 slashing damage and gain a +1 bonus to damage rolls against beasts. On subsequent turns, you can use a bonus action to revert the  weapon’s form.