You can get Tristana and Alistar for free by liking them on facebook and subscribing to their youtube, respectively. They might be a good start.EskimoJoe said:I'm good with Morgana. After getting all my runes, I never bought anything else. I'll occasionally try someone new, but never bought anyone. I guess I also have Kayle, but she was free, so...
I'd consider Xerath and Morg a bit too similar. Branch out to a different role like tank or AD carry. You don't want to get in a Draft game where the first 2 people pick AP carry and suddenly you are playing as a 3rd AP carry or a char you have no experience with.