Yes. You need to hold the arcane focus for it to substitute as a material component.
Does a wizard need an arcane focus?
Schools of Magic. In order to use a spell focus, a character must have at least 1 level of wizard and have the ability to cast arcane spells. First-level wizards begin play with a spell focus. While they are not required to use foci, most wizards do.
What’s the point of an arcane focus?
An arcane focus is a Special item designed to channel the power of arcane Spells. A Sorcerer, Warlock, or Wizard can use such an item as a Spellcasting Focus, using it in place of any material component which does not list a cost.
Can you cast a spell without a focus?
Yes, you can cast prepared spells which require only Verbal and/or Somatic components when deprived of your focus. (As long as you can produce the Verbal and Somatic components, that is.) The focus only functions to replace (subject to the limitations you mentioned) such Material components as are required.
What happens when you use your Arcane focus?
Your arcane focus will never be used up. Some spells consume their material components though and those spells have notes in their descriptions saying that the material components are consumed by the spell. Protection from Evil and Good is a spell where the components are consumed by casting the spell.
Can a focus prevent somatic components in spellcasting?
A free hand to do somatic components for S (but not M spells) – an occupied hand, even when occupied by a focus, doesn’t meet this requirement (without feats). A free hand to handle components for M (but not S spells) – this hand my be occupied by your focus, which could be a shield, weapon, or instrument depending on class/subclass.
Do you need a free hand to cast a spell?
Spells that require a verbal component only require the use of your mouth, however Somatic and Material components require a free hand: Spellcasting gestures might include a forceful gesticulation or an intricate set of gestures.
