Bloodline SMP is a custom Minecraft SMP built around bloodlines, ability progression, unique combat styles, custom items, and competitive PvP. It takes the usual SMP format and adds a more structured combat and progression feel, so there is always something to work toward while you play.
The server also uses a companion client mod for the full HUD experience, which helps tie all the custom mechanics together and makes the whole setup feel a lot more polished. If you like SMPs with a stronger PvP edge, custom systems, and a more detailed survival feel, Bloodline SMP is aimed right at that.