D&D 5E Can a cleric use his weapon as a spellcasting focus?

[Fanaelialae]

Charging a spell sounds cool and you can let your player do it as flavoring, but require the actions to be spent. One turn to cast the spell, a second turn to swing and hit, dealing both damages. This conserves the action economy well enough. The risk being their chance to miss the swing and miss both spell and attack.

The potential issue here is if the PC can cast the spell as a "pre-buff" before the encounter is engaged, thereby breaking the action economy by allowing for a devastating opener.

 

[aco175]

At 8th level life clerics cast spells with a divine bonus of 1d8. Not sure if you can swap out something else for similar.

I can also see using a weapon to cast spells. The one hand free thing using a shield allows to place your weapon in the same hand that the shield is so you leave one hand free. I can see just using the weapon without a shield to still have a hand free. You give up the shield bonus to still e able to cast. It would be ok with me.

 

[Mistwell]

Our cleric (of Apollo) wants to cast spells through his weapon- specifically, he wants to temporarily charge the weapon with a spell, which will be cast on the enemy when he attacks with it. Are there existing rules that could support this? If not, what could I put together that would still be balanced? The party is level 11 at the moment.

I would allow the weapon to be used as the focus instead of the shield (though understanding you've now risked being disarmed of your focus if you're disarmed of your weapon).

Noteworthy here, we're talking about a cleric weapon attack which...simply isn't that much damage. It's generally d6+str, with strength being a secondary stat for the cleric, so we're likely talking about requiring an attack roll to add an extra 5.5 points of damage to an attack. It's certainly helpful, but we're not talking about the same as adding an extra fighter attack, or an extra spell attack on top of a second spell attack. So that's the context of power we're talking about with this. If your Apollo cleric tries anything tricky which would bring the damage we're talking about well outside that rough estimate then I'd adjust this advice accordingly to be more costly to use this power for the cleric.

Charging the spell, that's sort of similar to two different methods which exist in the game: a cantrip, or a magic item.

For the cantrip method, simply adding that kind of lower amount of weapon damage to the casting of a spell is somewhat similar to the cantrips green flame blade or booming blade. I'd use those as the model, if you want to use a cantrip as the method of doing this. So it would be something like this: "Apollo's Smite (Cantrip): Cast this spell as a bonus action and simultaneously make a melee weapon attack against a foe. If your attack hits, apply damage as normal and you may now cast a Cleric spell which targets a single target, with the same foe that target. Apply all normal requirements for the spell (an additional spell attack, saving throw, etc.)." Or something like that (that's a bit of sloppy language there I am sure others can tighten up).

If instead you want to go the method of a magic item, it's somewhat similar to a frost brand weapon. Which doesn't add your strength bonus again to the damage, but still it's pretty close. I guess that's what I'd use as the baseline for this - a magic item like a frost brand. Which would make it "very rare".

 

[Bacon Bits]

Our cleric (of Apollo) wants to cast spells through his weapon-

Using it as a weapon focus is fine, particularly if the cleric was of the War domain. Personally I wouldn't put it in Apollo's wheelhouse unless it were a bow, but you can do what you'd like. As others have said, it's not going to be broken because the books give an example of a shield emblem in the description of a holy symbol on PHB 151.

specifically, he wants to temporarily charge the weapon with a spell, which will be cast on the enemy when he attacks with it. Are there existing rules that could support this? If not, what could I put together that would still be balanced? The party is level 11 at the moment.

That's a horse of a different color.

The "rules as written" version of this would be to say, "Take two levels of Paladin and gain the Divine Smite ability," although the character would probably want to take five levels of Paladin to get Extra Attack if he's so focused on combat. If you want to do it as a reward, you could just grant the ability outright or let the player spend their ASI at level 12 for it, but it's not a minor ability.

Another option would be to create a weapon that lets you cast a specific spell X times per day, or perhaps a weapon that would allow you to use Divine Smite 3-5 times per day.

If we're looking for a more direct equivalent, I don't believe it's in 5e, but 3.5e had a Spell Storing weapon modifier:

A spell storing weapon allows a spellcaster to store a single targeted spell of up to 3rd level in the weapon. (The spell must have a casting time of 1 standard action.) Any time the weapon strikes a creature and the creature takes damage from it, the weapon can immediately cast the spell on that creature as a free action if the wielder desires. (This special ability is an exception to the general rule that casting a spell from an item takes at least as long as casting that spell normally.) Once the spell has been cast from the weapon, a spellcaster can cast any other targeted spell of up to 3rd level into it. The weapon magically imparts to the wielder the name of the spell currently stored within it. A randomly rolled spell storing weapon has a 50% chance to have a spell stored in it already.

Note that the ability was restricted to melee weapons, so spell range wasn't a consideration of the design. 3.5e classifies it as a +1 equivalent, which is the weakest category of weapon enhancement. As such, a magic weapon with an equivalent ability in 5e would not be too far out of line, especially at level 11. I would probably make it a +0 or +1 magic weapon at most. A 5e version would probably also require the spellcasting to cost a reaction because casting spells is harder in 5e, but that's somewhat fiddley for a homebrew item.

From the default Cleric spell list, I would include:

Cantrips: Sacred Flame, Spare the Dying, Toll the Dead

1st: Command, Cure Wounds, Guided Bolt, Healing Word*, Inflict Wounds, Sanctuary*

2nd: Aid, Blindness/Deafness, Gentle Repose, Lesser Restoration, Protection from Poison, Warding Bond

3rd: Dispel Magic (creature target only), Feign Death, Life Transference, Remove Curse, Revivify, Sending, Tongues, Water Walk

Anything in italics would be technically legal, but would be really narrow in use. Many of the cleric spells are willing creatures only or are beneficial to the target. It's a pretty limited list for Clerics. Note, however, that other characters in the party could charge the weapon. Vampiric touch was the 3.5e spell that was classically paired with the weapon.

 

[Hawk Diesel]

I'm with @Mistwell here. I would talk to the player and ask what they are envisioning to be able to cast through their weapon. Then use the weapon cantrips (green-flame blade, booming blade, ect) as models for a signature cantrip for the cleric.

Otherwise, if the player is adamant about being able to use spell slots, you can ask about the spell(s) he wants to cast through his weapon and develop smite spell versions (such as branding smite, banishing smite, ect). Then either allow the player to do research as a downtime activity for the spells, or create an in-game opportunity to earn the ability to cast those new spells. Or just give them to the player if you don't wanna go through all that. Questing for specific powers/items/whatev is fun for some groups, but it's not everyone's cup of tea. Especially if you're in a very story-driven game or a portion of the campaign where it would be difficult to find the time for side quests.

 

[aco175]

Flavorwise the charging the weapon part can work. A spell like sacred flame cast with your free hand while holding a shield or just a weapon and no shield can just as easily be cast through the weapon for flavor and not affect the game and the rules. I would not allow using the weapon as the free hand but just for flavor. Same way as a death god may cast sacred flame showing something different than the god of healing. Same affect but different flavor.