We have rotated the set of free Champions for Week 8 and posted the lineup for Week 9. The Champions that are free this week include Poppy, the new Champion. Since launch we have now had every Champion free for one rotation (check the chart).
Here are the Week 8 Free Champions:
Blitzcrank (Tank) Corki (Mage) Katarina (Melee DPS) Malphite (Melee DPS) Rammus (Tank) Sivir (Ranged DPS) Soraka (Support) Veigar (Mage) Udyr (Melee DPS) Poppy (Tank)
Amumu Tank Ashe Ranged DPS Cho'gath Tank FiddleSticks Mage Heimerdinger Support Jax Melee DPS Ryze Mage Twitch Ranged DPS Warwick Melee DPS Zilean Support
Also - here's how we choose the free Champions: