Ezreal

Ezreal is free this week, i've been waiting for this what seems forever!

Check out this guide: http://www.mobafire.com/league-of-legends/build/booshidos-ad-ezreal-43156 if you wish to rape as him.

Ahri, the Nine-Tailed Fox

Champion spotlight has just been announcing the new champion, who will most likely be free to play for a week over the Christmas period. Very interesting mechanics!

http://euw.leagueoflegends.com/news/champion-spotlight-ahri-nine-tailed-fox

Sona, possibly the best support

She's free this week, played 3 games so far - won all 3 games.

She definitely turns the tides of all team fights.