Champion of the Titan Games (Dragonwatch) (Dragonwatch, 4)

The Titan Games are a popular event lead by Humbuggle, a powerful troll. A giant stadium brings people from all over. There they watch gladiators battle. It is all part of of a long scheme of games to allow the victor to take a precious stone which grants immense power. Seth goes there in an attempt to gain his memories back. In the process he runs into separated memories (that he helps cristen as "Reggie"), a satyr professor and many other beings. 

Meanwhile, the dragons have their eyes on world domination. The dark unicorn has taken over the fairy realm. The Giant realm is one of the last sanctuaries they want to take over. This realm also happens to be the realm that hosts the Titan Games. The giants treat the dragons as enslaved beasts of burden. There is plenty of built up dragon resistance to the giants. The giants themselves are also too prideful in their power. They don't think they have to work much to protect themselves. Alas, pride comes before the fall.

Seth's final quest to get his memories back takes some turns. The direct route isn't necessarily the best one. Sometime there need to be sacrifices to achieve the desired goal.