A wizard must prepare a list of spells they have available to cast. A wizard could cast a cantrip without “preparing” it, but cantrips are not spells “from his [spell]book”. The only way to cast a spell from your spellbook without preparing it is if it is a ritual (PHB, p. 114):
Can you cast spells without a spellbook 5e?
1 Answer. Yes, you can cast spells without your spellbook. And yes, your list of prepared spells will stay prepared until you prepare a new list. In the Preparing and Casting spells section, only preparing a new list of spells actually requires your spellbook.
What happens when you cast a spell for longer than one action?
When you cast a spell with a casting time longer than a single action or reaction, you must spend your action each turn casting the spell, and you must maintain your concentration while you do so. If your concentration is broken, the spell fails, but you don’t expend a spell slot.
What are the rules for casting a spell?
When you cast a spell with a casting time longer than a single action or reaction, you must spend your action each turn casting the spell, and you must maintain your concentration while you do so. If your concentration is broken, the spell fails, but you don’t expend a spell slot. If you want to try casting the spell again, you must start over.
When can you counterspell a spell with long casting time?
If a spell has a casting time of 1 minute, they are casting for that 1 minute and if you see them you may counterspell. If the casting time is 1 action you must immediately spend your reaction to counterspell or miss your window. You attempt to interrupt a creature in the process of casting a spell. The key here is interrupt.
Why do I lose concentration when casting a spell?
The following factors can break concentration: Casting another spell that requires concentration. You lose concentration on a spell if you cast another spell that requires concentration. You can’t concentrate on two spells at once. Taking damage.
