"Their work is singularly incompetent, but they struck gold seemingly by accident – ” Warlock (Book 2, Chapter 5: Recognition)
Bumbling Conjurer is a heroic name is associated with both magic and comic relief.
Power Level 
The Name is middle tier in power. The most recent user was unintentionally able to redirect the scrying of one of the Calamities, Warlock. The most recent user was also able to inhibit Apprentice's spell casting due to the unpredictable nature of the Bumbling Conjurer.
Despite it being a Name that is geared towards magic, it is also relies heavily on luck. The user is immune as long as their accidental failures result in comedic triumphs. This results in any action of harming or being harmed backfiring on the assailant in comic ways. The comedic portion of the Name can also backfire on the Named causing their spells to fizzle out at the worst times or causing them to slip on their own robes.
Special Abilities 
The name augments the user's magical capacity, allowing them to cast an assortment of spells. Despite their increased power due to their Name they lack accuracy. The conjurer might intend to cast a spell but might be blown back into a wall causing a chandelier to drop on their foe. The foe will be dispatched but not by the intended means.