Updated plugin page for 2.0 version, the old 1.3.6 was archived on github under the name castle-siege-legacy Castle Siege 2.0 brings:

• Multi-Arena System
• Configurable guis, kits, messages, menus, abilities, kill effects, scoreboards etc...
• Gradient scoreboard support
• Placeholder API integration
• New MAP Regeneration system using FAWE and Regenerato