CaveClan

Cave Clan is the simplest survivability for the whole board: cheap heroes reach (2) in the first rounds, and (4) with its large health boost comes together by the mid game and makes the team noticeably thicker against any damage type. (6) needs the expensive heroes and adds more health the more player health you have already lost, making it a synergy for a player who is behind and wants to claw back through survivability.