The Vicious Summoner is a pretty good all around and class and in my opinion one of the most fun to play. They can lead an AE or AOE group reasonably well as they have decent HP and defense. The Vicious Summoner also has a summon so that adds one more mob to the train that would otherwise not be there due to the agro system in 2Moons. The Vicious Summoner does a lot of damage with spells and summons. All in all probably the most well rounded class in the game, the guy leading our guild in the game plays a summoner and he is nearing 100 currently and loving it. Here's a link to the Vicious Summoner skills and abilities:

http://2moons.mmosite.com/guide/class/vicious_summoner.shtml