Alters = Position that doesn't shoot at you when fighting the owner of said alter.
This is a GREAT idea! If you don't have a tower etc defending a point, it encourages teams to fight over it much easier than fighting over a tower! The only drawback is they need to make sure its accessible by people that are a bit behind, like having the first two turrets down where they are stuck in their base etc.
Overall, I'm looking foward to a much more open map! Think of it this way guys. Where not going to get a new map for a while since there concentrating on the change to items/jungle in SR. Plus, TT is so annoying - mostly to walk from bot lane to top through the middle. Most annoying path ever T_T