I noticed this nice combo lately and it seems like there isn't written anything about it.
Graverobber+Border Village isn't a game-changing combo à la Chancellor/Stash where you can ignore most of other cards and go for it, but its maybe the most power combo of the "When-gain-cards+trash for benefit" ones.
How it works
Border Village let you additionally gain a cheaper card. In this combo, you mostly will take some drawers and/or thinners for get the engine working, later on you take graverobbers with the BVs. So now (in a engine with small deck or good draw), you can trash the BV with graverobber and gain a province/another BV+5$-card and with the second graverobber you can grab the BV back from the trash (what is neat if the supply pile is already empty) , gaining a further Graverobber/strong $5. So you can basically get Province+$5-card out of 2 Graverobbers.
Strenghts
Endgame
At the and of the game, you have lots of options. You have a huge amount of cards, that you can graverob into a province (BV, Graverobber, other $5s from BV), and you can get Duchys by graverobbering back BVs.
And since Graverobber topdecks the gained card, you can almost ensure that you have some BV together with your Graverobbers, either for producing actions or gaining provinces.
Getting massable $5s quickly
Once your engine is running, you're able to grab many 5s for keep your engine going and later to trash them into provinces. Cities comes in mind. I haven't tried it because it's already a 3-card-combo, but it should work well, though. They make sure you have enough draw and actions and can lead in a megaturn buy turning multiple Cities/BVs into Provinces at once.
With special cards:
Embargo: Just put the embargo token on provinces and/or Colonies. The Tokens don't care you much, because you don't buy your important cards, you gain them via Graverobber or Border Village. The only card which can hurt you when being embargoed is BV itself. If there's some trashing, you could still buy some BVs, but not to much, then you're ruining your advantage by empty the curses.
Weakness
Opponent's Graverobbers
If you are trashing much with Graverobbers, you're not safe to get them back. Your opponent (especially when he went the same strategy, but also as a little counter) can steal you the BVs from the trash and profit on his own.
Colony games
The combo works when the cards to gain are $5-$9, but $11 is unreachable for Graverobber. The only thing you can do is a province rush or end on piles after a few provinces, but you will fail most of the time against a wellbuilt colony-oriented engine
Have you any thoughts of this combo or additional comments to strenghts or weaknesses I've forgotten?
