I'm building a variation on the Palalock combo build from this Q&A, and noticed that Warlocks can use an arcane focus for their spellcasting. Since Paladins already cast through a divine focus (holy symbol), would it be possible for my character to have an item that's both an arcane and a divine focus for spellcasting purposes? It'd save the character a fair bit of juggling, and also not tip people off nearly as obviously to the character's capabilities unless they had an arcane background to begin with...
- Arcane Focus and Holy Symbol appear to be different "types" of items.
- Arcane Focus lists: crystal, orb, rod, staff or wand
- Holy Symbol lists: amulet, emblem, reliquary
- So barring some special item (a crystal amulet?) you would need one of each.
You have flexibility here. From PHB 203:
A character use a component pouch or a spellcasting focus in place of the components specified for the spell... A spellcaster must have a free hand to to access these items, but it can be the same hand that he or she uses to perform somatic components.
So for most spells you can use any one of the following:
- A spellcasting focus.
- A component pouch. (25gp)
- The actual component listed in the spell.
You want to avoid juggling items and revealing your capacities. This means you have at least the following options:
- Two necklaces (Crystal and Amulet). Grab the one you need for the spell you are casting. Could also be tied to your belt, but that's more obvious. Or you could tie them together on the same chain, they weigh 2 pounds combined and you get a free object interaction each turn, so "switching" is not a big deal.
- One focus, one component pouch. If you wear your holy symbol, nobody knows about your arcane magic. The component pouch can easily be written off as cheap medicinal herbs or some special components. Use these only for your Warlock spells. You could even just use the same component pouch for both classes.
- Pay close attention to your spells. Many of them don't require any Material components. For the Warlock: Eldritch Blast, Hellish Rebuke, Mirror Image, Misty Step, Ray of Enfeeblement are all usable spells with no Material Component. For the Paladin: Cure Wounds, Compelled Duel, Smites all require no Material components. You may be able to assemble a spell list with no Material Components required.
Sorry, but by RAW, the items lists for Arcane Focus and Holy Symbol are unique and separate.
An arcane focus can be a Crystal, an Orb, a Rod, a Staff, or a Wand.
A holy symbol can be an Amulet, an Emblem, or a Reliquary.
You can try to convince your DM to something like combining the AF Crystal with the HS Amulet, but that would be house-ruling. ;)