Rogue sneak attack rules question, now that it's 1/turn

[DracoSuave]

I agree that this works RAW, but I wouldn't allow "the next turn starts" as a valid trigger.

Absolutely.

Readied actions require an specified observable action as a trigger. You cannot observe 'turns beginning' nor is it an action. You cannot use 'He does anything' because that is not a specified action. As well, even if you could, you do not use your reaction until his 'anything' is done. He'd still get the action off.

They also require a specified action as the result. You have to choose a specific power to use, not just simply 'I'm going to do something if he does anything.'

Lastly, readying an action is not inherently a secret. The strict narrative of it for obvious reasons is based on context, but the basic gist of it is, you generally can tell if someone is getting himself ready to do something.