Quote Originally Posted by Rukelnikov View Post
Consider this case now:

5th lvl wizard readies action to launch a crossbow bolt at an enemy spellcaster when its starts to cast a spell.

Enemy spellcaster declares casting of Wall of Fire.

5th Wiz realizes enemy spellcaster is doing the components for some spell, he can cast Counterspell to disrupt it, but he cannot pull the trigger?
Its also worth just reiterating that this is a game.

Why is a character capable to perfectly jumping the exact same distance every time? Why can only level 20 dex based character whose focused on training with a bow attack 8 times in a round (a fighter) while another can only attack once (a rogue)? Why does a rogue always strike for substantial damage only when he's hidden or an enemy is standing next to his opponent, can't he get lucky? Why do PCs sit there and watch enemies stab their unconscious friend, only leaping into action when its their 'turn'?

The answer to all these things is nothing to do with logic and everything to do with the type of game 5E wants to be. So the reason you can counter a spell with Counterspell and not with a crossbow is nothing to do with the timing and mechanics of firing a crossbow bolt at a man in a funny hat in the real world and everything to do with the fact that we're looking up the rules for Readying an Action in a RulebookTM.

A Counterspell can interrupt because the rules says it can. A Readied action triggers when the triggering action finishes because the rules say it does. Obv you don't have to play it that way in your living room (I usually wouldn't allow it to interrupt but would probably allow exceptions depending on circumstance), I ain't the boss of you