Formicary is a good Weyland sentry. It's no Archer, Surveyor, or Colossus, but it is a cheap sentry you can slap down on your remote and then have magically defend your centrals when you need it to. Its sub isn't the greatest in the world, it lets the Runner pick their poison after all, and its rez-to-break ratio isn't all that great either, but it's effect is punishing enough that Runners would rather just end the run if they facecheck it and its effect practically begs the Runner to facecheck it when they least expect it to. I think 2 creds for it is a steal, honestly. Also, Formicary was the central part of a hilariously degenerate combo that led to the first banned NISEI card. Since it had the exact same trigger as Cayambe Grid you could choose to let Cayambe fire first, then Formicary, then Cayambe again after the runner breaks the Formicary, then any other Formicary you had laying around, then Cayambe again, and so on. It was not unusual to force the runner to pay 30+ creds on a single run. That was a wild time.