For the amusement of the boards, a chat log from a game today. Its a board with wharf on it, and my opponent as first player has just opened 5/2 with wharf, to my 4/3 silver/silver.
Things start to look bad as he acquires an early Bank before I've even hit $5, and I realise that I am looking at a high likelihood of game loss. So I buy a potion, then manage to acquire a Possession.
0:46 Asklepios: gl
0:48 i beat you: pocssesion require no skill
0:48 Asklepios: Interesting thought
0:49 Asklepios: I'd say its a weak card certainly
0:49 i beat you: lol not really
At this stage, just to make his point he buys a potion (with $7 and two buys, no less). He has a massive cash lead, two wharves, two banks. I have less cash, one Possession, one Wharf, and am now desperately buying Warehouses and Apothecaries in the hope that I can play his (stronger) deck often enough to gain an advantage in green cards.
Worth noting that he never bought a Possession, and fell short of a Province by $2 in a potion hand at least once.
0:49 Asklepios: And normally I'd reject it in favour of say 2 wharfs + money
0:50 i beat you: i say its dumb
0:50 i beat you: owwowow
0:50 i beat you: gay
0:50 i beat you: i hate this
0:50 Asklepios: resign then
0:51 Asklepios: fact is you're likely to win from a 5/2 opening with wharf on the board
0:51 Asklepios: possession increases variance
0:51 Asklepios: hence it was a sensible play when starting from a weaker position statistically
0:52 Asklepios: Here, check this link if you believe its an overpowered card, as it really isn't.
0:52 Asklepios: http://dominionstrategy.com/2010/12/03/alchemy-possession/
0:53 i beat you: lol its just i once played poccession with kings court and i literally was about to flip on this guy
Note that if resigning didn't count as a game lose, I'd usually disconnect when someone uses "gay" as a perjorative.
Still, I've learnt to try to meet ignorance with education...
0:53 Asklepios: essentially the turn i buy possession, i could have got a province if that potion was silver
0:53 Asklepios: so i need at least two provinces off it to make it worthwhile
0:53 Asklepios: not counting the action economy from not playing wharves
0:53 Asklepios: but it was my only hope as you had reached wharves and big moneys first
It goes a bit wrong, as I have to hit duchy then province to keep ahead of the PPR, so I risk hitting his Wharf on a Possessed turn, and draw a slightly larger worthless hand. Luckily his enhanced next hand only nets him a duchy, at a stage when a province would have been disastrous.
0:54 Asklepios: ah shame to have to feed you a wharf drawBut keeping close tabs on the score, I grab a duchy and an estate so that if he gets the last province he'll lose.
Luckily this doesn't turn out to be an issue, as I possess him again in time to grab the last Province for a solid victory.
0:55 i beat you: wow so gay
0:55 i beat you has returned to the lobby.And, uh, gg to you too, I suppose.
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Amusing anecdote aside, I think its fair to say that Possession creates higher variance. Like many cards, its a decent desperation play when you know that a more conventional game has you at high odds of losing.
But Jfrisch is right: its normally a trap, as my opponent demonstrated by grabbing a potion he never used, and compromising his stronger opening luck because of it.
I'm entirely happy though that it takes as much skill to play and play against as any other Dominion card. Yes, it can warp the game a little, and yes it does force you to adjust your strategy when your opponent buys one or more copies of it. But most good cards do!
edit: and here's the game link:
http://councilroom.com/game?game_id=game-20120416-165541-50064918.html