I am enamored with the concept of living spells in D&D…it began with the release of a Living Bigby’s Hand; and snowballed into all the other “living” spells that have been officially published…”Cloudkill”, “Unseen Servant”, “Lightning Bolt”, etc…

So keen on the concept; I’ve even introduced a subplot to my campaign where a magical phenomenon has wreaked havoc with the spells that Wizards and other arcane practitioners cast; resulting in the spells immediately gaining consciousness and striking off on their own, until they are all roaming the countryside, causing chaos.

My question then, is that should the players encounter one of these “wild” spells in their journey…would it be appropriate to use the “Arcana” skill in a manner similar to the “Animal Handling” skill?

That is to say, does it seem appropriate that these spells would have a sort of intelligence that makes an “Intelligence” based skill like Arcana a reasonable way to socially interact with them…perhaps even circumventing combat encounters altogether, if the “Arcana” roll is high?

Or would it be simpler to stick with the Charisma based skill checks like “Persuasion” or “Intimidation”?

Or perhaps both?

Seems appropriate to me. Another option would be a nonstandard stat/skill combination like Persuasion (Intelligence) or Arcana (Charisma).

You are the DM, so it is 100% up to you and what you think makes sense.  Personally, I would use Arcana in place of an animal handling check.  You could also have a player proficient in Animal Handling roll an Intelligence Animal Handling check in place of the standard Wisdom Animal Handling check.

I would not do a charisma check on one of these myself - charisma is about using mannerisms and words to persuade higher orders of creature, and it sounds like you want these to be akin to regular beasts in terms of intelligence and general bearing.  That said, you are the DM, so if you want to let players use Charisma checks (you could also do a Charisma Animal Handling check) that is your choice.

Quote from Caerwyn_Glyndwr >>

You are the DM, so it is 100% up to you and what you think makes sense.  Personally, I would use Arcana in place of an animal handling check.  You could also have a player proficient in Animal Handling roll an Intelligence Animal Handling check in place of the standard Wisdom Animal Handling check.

I would not do a charisma check on one of these myself - charisma is about using mannerisms and words to persuade higher orders of creature, and it sounds like you want these to be akin to regular beasts in terms of intelligence and general bearing.  That said, you are the DM, so if you want to let players use Charisma checks (you could also do a Charisma Animal Handling check) that is your choice.

 It’s a peculiar scenario where I believe someone proficient in Arcana would realize that their somatic & verbal gestures actually serve as a “language” which allows them to communicate with these living spells.

I am also enjoying the idea that these “charismatic” characters find themselves in a situation where their natural charms or lies do not work against these beings of pure magic.

With regards to the intelligence of these living spells…I think it will depend on the spell.

For the purposes of destructive spells, they will likely have very little intelligence, and seek mainly to lay waste to anything around them.

Spells like “Unseen Servant” or “Bigby’s Hand” will possess a degree of rational intelligence, I believe…these will be the sorts of spells the party has a chance of negotiating with (as they emulate humanoid mannerisms to an extent).

Funnily enough, this whole phenomenon will have occurred because a group of wizards thought it would be a GREAT idea to bestow sentience upon the “Wish” spell…so I’m entertaining a high-level scenario where that might actually happen.

I 100% believe that you can use Arcana to handle the living spells like you would Animal Handling.

...and by the way, if you want any more Living Spells, check out the link in my signature. 

Dragon magazine, issue 419, has an article on sentient living spells. If you can find a copy somewhere it may be worth reading.

Quote from Tony1Adobe >>

 It’s a peculiar scenario where I believe someone proficient in Arcana would realize that their somatic & verbal gestures actually serve as a “language” which allows them to communicate with this living spells.

 
This is a great idea!