Can you end your right after you cast a spell, skipping your other phases, so it will not be countered? I was playing EDH/Commander and my opponent was casting his commander, {Tajic, Blade of the Legion}. I had {Geist Snatch} in my hand and the four lands to play it. But as soon as he played it, he just called "turn," so I couldn't counter it.
You still get to respond to Tajic's casting, he's wrong you can counter him
Magic would be hilarious
Is there a specific rule that can help me out? My opponent happens to be a stubborn ten-year-old lol
The phases of the game are part of the game. Attempting to skip phases especially for an advantage will get you kicked out of any tournement. The phases are not there as a recomendation they are there as the steps you must take. I will not quote the entire phase section or the entire casting a spell process, but I will try to find the rule that will shut him up.
608.1. (http://imtgapp.com/forum/index.php?action=imtg;area=rule;number=608.1.): Each time all players pass in succession, the spell or ability on top of the stack resolves. (See rule 609, "Effects.")
That says his spell does not resolve under his magical candy land rules of ending the turn whenever you feel like. I might sound harsh but playing a game with people who don't know and refuse the rules makes you worse at the game. It is the only type of practice that is counterproductive. I hope he starts learning the game or no one will want to play with him.
There is a card that ends the turn by skipping phases but read the text on it closely {Sundial of the Infinite}
I like {time stop} more, but even these must be allowed to resolve first.