Data Ward is a ten-meter metal door ready to lock the Runner in forever once you find the right lock and, in the meanwhile, it's a ten-meter metal door that isn't easy to get through. It's a one-card solution to at least three or four problems NBN usually has and wants to solve.
1) It completely locks the Runner out after Midseasons/HHN. There are no "easy" ways around it and it will stop glory runs while you wait for your Boom.
2) It can be used to create very powerful remotes with a small investment in both credits and slots. Data Raven into Data Ward isthe most obvious one but it can also be combined with IP Block or even Turnpike for a similar effect. This allows NBN, for example, to score bigger agendas, create extremely taxing SanSan trashing runs and play Reversed Accounts.
3) While not overly efficient on its own, a 3 credit tax that punishes facechecking is not bad and can be a good way to get the ball rolling. For example, Ward into Reversed Accounts is a 6 credit swing, enough to enable Hard-Hitting News or Stinson at the earlier stages of the game.
4) It's resilant. It cannot be passed by D4v1d, it's not cheap to bypass with Femme Fatale and has both a high number of subroutines and a high-strenght, making it almost impassable with Faust alone (7 cards). It's also a barrier, making it easy to protect to Cutlery and making it impervous to Yog. It just works.
One of my new favourite pieces of ICE for sure.