Silence:
For the duration, no sound can be created within or pass through a 20-foot-radius sphere centered on a point you choose within range. Any creature or object entirely inside the sphere is immune to thunder damage, and creatures are deafened while entirely inside it. Casting a spell that includes a verbal component is impossible there.
How does this work in practice?
Say an enemy wizard is 40 ft away and casts a 60ft range spell that requires Verbal (V).
- If I’m standing inside a sphere of silence can his spell affect me?
- If I’m not in the sphere of silence but the wizard is can the spell affect me?
- If the Wizard is in the sphere of silence, are they immediately aware they’re in the sphere (and will thus use their turn for non-verbal things) or are they oblivious to this and would have to first try to cast a V-Spell and then question why it didn’t work?
- If we’re in something like a 10 ft wide hallway that’s 200 ft long. The Wizard is at the far end but already starts shooting spells at us. Would placing the Sphere of Silence at its maximum 120 ft prevent any of the Wizards spells from passing through it since there’s nowhere else for the sound to travel?
- How will I even know if the Wizard I’m facing is using a Verbal spell if the DM doesn’t always act it out to that level of detail?
If I’m standing inside a sphere of silence can his spell affect me? Yes: a cast spell is unaffected unless there is thunder damage, or you need to hear the caster like with Compulsion, Vicious Mockery, Suggestion or Divine Word.
If I’m not in the sphere of silence but the wizard is can the spell affect me? His Verbal (V) spell could not be cast because the verbal component cannot be met.
If the Wizard is in the sphere of silence, are they immediately aware they’re in the sphere? He would notice the lack of sound (the silence is literally deafening), but might not know the cause.
Would… the Sphere of Silence… prevent any of the Wizards spells from passing through it? No (as per the first answer above)
How will I even know if the Wizard I’m facing is using a Verbal spell? The vast majority spells do require a verbal component, so just remind the DM whenever a spell is cast in a sphere of silence (and maybe offer to look up the spell for him in the PHB, which can be a pain)
The phrase “Casting a spell that includes a verbal component is impossible there” merely refers to the inability to meet the verbal component when casting (like with being gagged), but it does not limit targeting once the spell is cast.
Verbal (V)
Most spells require the chanting of mystic words. The words themselves aren’t the source of the spell’s power; rather, the particular combination of sounds, with specific pitch and resonance, sets the threads of magic in motion. Thus, a character who is gagged or in an area of silence, such as one created by the silence spell, can’t cast a spell with a verbal component.