At round 1, I ready a spell, say, magic missile, but the trigger happens at round 3. At round 2 and 3, can I cast spells with my action as normal (considering the rule about concentration)?
There was info in a Sage Advice tweet recently if I remember - trying to dig it up. I believe you are correct though - the readied spell takes concentration (and can be lost if you lose concentration).
When you ready a spell, you cast it as normal but hold its energy, which you release with your reaction when the trigger occurs. To be readied, a spell must have a casting time of 1 action, and holding onto the spell's magic requires concentration. If your concentration is broken, the spell dissipates without taking effect. For example, if you are concentrating on the web spell and ready magic missile, your web spell ends, and if you take damage before you release magic missile with your reaction, your concentration might be broken.
So, for your example, it would not work. If you ready a spell and don't cast it (using your reaction) before the start of your next turn, you lose the spell slot. If you don't cast the readied magic missile before the start of your turn on round 2, then your spell slot would be wasted. Jeremy does mention in that tweet thread that he house rules being able to use the action on the subsequent round to continue readying (I have this house rule as well in my games), but that would be up to the DM.
This is the situation:
At round 1, I ready a spell, say, magic missile, but the trigger happens at round 3. At round 2 and 3, can I cast spells with my action as normal (considering the rule about concentration)?
There was info in a Sage Advice tweet recently if I remember - trying to dig it up. I believe you are correct though - the readied spell takes concentration (and can be lost if you lose concentration).
https://www.dndbeyond.com/compendium/rules/basic-rules/combat/actions-in-combat#Ready has the following:
Site Rules & Guidelines || How to Tooltip || Contact Support || Changelog || Pricing FAQ || Homebrew FAQ
If you have questions/concerns, please Private Message me or another moderator.
Wary the wizard who focuses on homebrew, for he can create nightmares that you wouldn't even dream of
Okay I found the Sage Advice I was looking for - http://www.sageadvice.eu/2015/09/25/how-does-readying-a-spell-work/
So, for your example, it would not work. If you ready a spell and don't cast it (using your reaction) before the start of your next turn, you lose the spell slot. If you don't cast the readied magic missile before the start of your turn on round 2, then your spell slot would be wasted. Jeremy does mention in that tweet thread that he house rules being able to use the action on the subsequent round to continue readying (I have this house rule as well in my games), but that would be up to the DM.
Site Rules & Guidelines || How to Tooltip || Contact Support || Changelog || Pricing FAQ || Homebrew FAQ
If you have questions/concerns, please Private Message me or another moderator.
Wary the wizard who focuses on homebrew, for he can create nightmares that you wouldn't even dream of
Ok thanks @Sorce. The whole point is that the ready action lasts for 1 turn, no matter what you ready.