Just wanted to make sure that this article got some attention, it is written by Nico Bohny, a great Vintage player and streamer who goes by shir kahn on MODO and streams on twitch at https://www.twitch.tv/busterbohny.
Nico, what are your thoughts on Abrupt Decay vs. Assassin Trophy post restrictions? I've tried all in on both, and both have their own restrictions. I'm leaning toward all in on Assassin Trophy because the uncounterable aspect of Decay doesn't seem to matter as much as being able to hit anything.
Additionally, Misdirection(s) to replace some number of Mental Misstep. I've been running 2 MisD and it's been great but I could imagine a situation, against Lavinia, that it would suck.
I scaled back on Tarmogoyf because the vanilla creature doesn't do as much in a combo meta. Some number is still useful as a roadblocks against Workshops and that sort of thing and a valuable green card to pitch to Force of Vigor. To replace some I've gone to maindeck Thoughtseizes, a very strong magic card against combo. Plague Engineer also seems a sideboard staple while people are playing elemental decks.
Personally I'm not a fan of the 3x GSZ builds that you have been playing. Would you continue to try and jam that? I'm not sure if it was actually ever good to begin with.