Magic The Gathering
 

My son (11 yo) just got back from a Boy Scout Camping trip where some of the kids were playing, and he got interested in it. I've never played.

What's a good starter-type pack/set etc. to get him to start off? I understand that the point is to build the deck over time; at this point, I'm really wondering what's a good start for a kid just getting into it.

A Deckbuilders Toolkit is not a bad way to start off.

This new set that just had its prerelease this weekend (War of the Spark) is a really fun set because it has 36 Planeswalkers. Normally a set only has 2-3 planeswalkers, but the storyline necessitated a huge abundance of them.

Is he just going to be playing casually or competitively? And if so, which formats?

He will start casually, I am pretty sure (he just noticed at the camping trip that some of his friends were into it). I am not sure of format (I am super super noob in this area).

Okay if it's just casual, not a big deal. If he gets into EDH/Commander (100 card singleton) or decides to play at a weekly tournament in a store, then there's different advice.

Oh, and if he's going to trade, make sure he uses TCGPlayer so that he doesn't get ripped off (or rip someone else off) in deals.