Game 2 against -Stef-: Is a Hunting Party Stack reasonable or is Double-Tactician a must?
I wonder if Possession is a concern here. Possession wrecks double Tactician. But maybe the game is not long enough?
Game 4 against -Stef-: Could I skip over IGG and go for a KC/Oracle/Festival/Baron/SP engine?
If there were trashing, I think you could. Without trashing, SP is awful against cursing, and KC/Oracle/Festival seems too unreliable in terms of what 5-card hands can start the engine.
Game 2 against Mic Qsenoch: Who should win this? The possessor or possess-ee. It is very close, and I bet it could swing either way game to game, but which strategy do you prefer? Or is it neither?
In this game, what he got from the 3 Possessions was: Wharf, Farming Village, Duchy, Farming Village, Duchy, Farming Village, Harem, City, Silver, Silver. (Also he stole your Wharf duration effect once.) Total value: 5+4+5+4+5+4+6+5+3+3 = 44. The cost for those Possessions can be valued at roughly 3*8 = 24. So it seems like they were cost effective in this game.
On the other hand, if they are Provinces instead, then MQ has 3 more Provinces at the end of turn 15, and at that point Possession had only been played twice.