My player is a monk 3/wizard 2 multiclass. To help him feel like a magic pugilist, I am using a house rule that allows his monk a Bonus Action to attack after casting specific cantrips. Since the cantrips Green Flame Blade and Booming Blade involve making a melee weapon attack, I've allowed the player to be able to make the bonus unarmed strike, so long as the weapon attack involved with the spell is a monk weapon.
This seemed like no big deal at first when he was low leveled. Now at level 5, these cantrips get a damage boost, and I'm worried his character may unfairly out-damage other players.
Can I allow this to continue, or should I say, "The damage increase is too much, from now on those cantrips will not combo with your unarmed strike bonus action"?
Best Answer
Well, it really is up to you, and you could wait to see how his damage output actually compares to the others. But for an idea of how powerful he is in combat, here's a comparison for you to consider.
The bonus unarmed strike from Martial Arts allows the ability modifier to the damage, effectively making them comparable to a fighter/wizard with the "Two-weapon Fighting" fighting style being allowed to use their bonus action off-hand attack after every time they use said cantrips.
However, a quarter staff is versatile, therefore a monk can use it two-handed for 1d8. This would mean our fighter/wizard needs the dual wielder feat to dual-wield non-light weapons, as no light weapon does 1d8 damage.
In regards to spells: the quarterstaff's versatility means that your monk can carry it one handed, freeing his other hand for somatic and material components of spells. To do this same thing, our fighter/wizard with the Duel-wielding feat would also have to take War Caster to be able to do the somatic parts of spells with weapons in both of his hands, and he still wouldn't be able to access any material components.
With your homebrew rule, your monk/wizard is effectively more useful than a fighter/wizard with two feats slapped on.