I think there should be npc drop ships for each race. Everytime the tyranids capture all the bases except for the main base a thunderhawk should come in and drop npcs to defend the base. Same for tyranids but a harpy should come in and drop in troops for tyranids if they lose all the bases. My idea is it should cost points for a thunderhawk or harpy to drop npcs but for a limited time but if they choose to drop imperial guards man for human it costs medium points if they drop space marines it costs all your points. For tyranids if they choose hormagaunts costs some points termagaunts all there points and the npcs can go from a minimum of 3 npcs to 5 your choice if you go with this idea. Basicly my idea is to make base capturing harder the npcs dont have to move they just sit their and defend the last point. But if the opossing alliance has npcs and they capture a base the npc should die or go away. this is my idea hopefully you can make it happen or choose to go with it.