Quote Originally Posted by JoeJ View Post
But you seem to think that perceiving somebody (who wasn't previously doing so) cast a spell and perceiving them start to cast a spell are different in some meaningful way. I don't, nor is there any rules support for that interpretation. So it remains: You ready an action for when somebody starts to cast a spell. They cast a spell and then you take your readied action.
I can ready for any perceivable trigger.

I ready an action for when someone starts talking. According to you I have to wait till they finish talking to shoot them?

If you say yes, well thats some free speech in your tables!

If you say no, then I can do the same for verbal components