This rod has an enormous ruby on its head, and it functions as a magic mace that grants a +3 bonus to attack and damage rolls made with it. 

You can telepathically use on of the following effects as a bonus action. One of these effects lasts until you use a different one.  

The rod becomes a flame tongue, as a fiery blade sprouts from the end opposite the ruby. (you choose the type of sword).

The ruby shapes into two crescent-shaped blades, transforming the rod into a magic battleaxe that grants a +3 bonus to attack and damage rolls made with it.

The rod's ruby sharpens into a spear tip, and the rod's handle lengthens into a 6-foot haft, transforming the rod into a magic spear that grants a +3 bonus to attack and damage rolls made with it.

The rod transforms into a handheld battering ram and grants its user a +10 bonus to Strength checks made to break through doors, barricades, and other barriers.

The rod assumes its normal form.

The rod also has four additional properties.

 Drain Life. When you hit a creature with a melee attack using the rod, you can force the target to make a DC 17 Constitution saving throw. On a failure, the target takes an extra 4d6 necrotic damage, and you regain a number of hit points equal to that necrotic damage. This property can't be used again until the next dawn.

Paralyze. When you hit a creature with a melee attack using the rod, you can force the target to make a DC 17 Strength saving throw. On a failure, the target is paralyzed for 1 minute. The target can repeat the saving throw at the end of each of its turns, ending the effect on a success. This property can't be used again until the next dawn.

Command. The Ruby Rod has 9 charges. While you hold the ruby rod, you can use an action and expend one charge to cast dominate monster, targeting a fiend you can see within 60 ft of you. 

Terrify. While holding the rod, you can use an action to force each creature you can see within 30 feet of you to make a DC 17 Wisdom saving throw. On a failure, a target is frightened of you for 1 minute. A frightened target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. This property can't be used again until the next dawn.

Notes: Archdevil, Damage, Control, Utility, Exploration, Combat