One thing I just noticed when glancing at the cards is that Outpost overlooks one of its big synergies with Tactician. Outpost is one of two cards (the other being Black Market) that currently allow you to play treasures with Tac every "turn". Take an ideal setup - Tac/Scheme/Outpost. Start on a Tac hand, play Scheme, play Outpost, play treasure; okay now buy whatever you want and return Tac to deck top. Outpost turn: draw 3 cards (one of them is Tac), discard them.
And there are a LOT of cards that let you get this sort of reliability - Scheme needs only one Tac, but you can use Haven, Courtyard, Mandarin, Count, Graverobber (requires a way to trash a Tac, but can let you really pound the provinces), and you can also use a second Tac with some "draw your entire deck" tricks. E.g. discard a Tac when you have an empty discard & draw deck with any discarder (e.g. Horse Traders); play Scout (one of the few times where Scout may be better than any other card), Navigator, Duchess, Scavenger, etc.; and now you can continue on to an assured Tac in your 3 card hand. This can be a very cheap setup as you can use your starting coppers to fuel big turns e.g. Courtyard/Tac/Opst needs just 17 coin to get into province range (buying a copper) and is quite reliable.
Which is part of the larger reason I'm sure Opst is undervalued by far. For engine decks, it becomes too easy to spend a turn overbuilding the engine so you can abuse stuff like Horse traders/Scout to setup your Opst turn and then cash in twice as fast.