From NexusClash Wiki
Wizard gains a passive +3 damage bonus with Firearms. In addition, they can use a charged attack option for 4 MP that can convert damage to Impact, Fire, Cold, Electric, Death or Arcane damage. This charged attack only works with Firearms' single-target attacks. When using the charged attack, any ammunition normally spent to perform that attack is not consumed.
If the Wizard uses the charge attack while having an aura Spell active (e.g., Death Mantle), the aura spell deals damage to the target as though the Wizard were using a close-combat attack. The wizard is not subject to the target's damage Auras in this case.
Note: Remember that the supplemental damage from the Wizard's aura will not stack with the supplemental damage from other sources, such as Martial Spellcraft. See the page on Supplemental damage for more information.