Originally Posted by
TkDodo
I think it's actually pretty good to slam the Stoneforge T2 in that situation. Frankly, getting it FoW'ed is a pretty good scenario anyway, since it indicates that the opponent cannot handle a resolved creature. Since he has both Ponder and Brainstorm in hand, he could realistically find another creature and play it on T3 if his SFM gets countered.
The Spell Pierce does probably nothing to protect the Stoneforge if you wait until T3: You cannot counter a FoW, because your opponent will have 2 lands in play. You cannot counter a Swords to Plowshares unless your opponent plays into it at end of your T3. You cannot counter a Thoughtseize taking away your equipment on your opponents T3. So the alternative to playing SFM on T2 is a) do nothing, leaving up Spell Pierce (for countering what exactly? there is no relevant T2 play you can Pierce here except a cantrip) or b) play Ponder in your turn, which I would rather do later to find solutions to problems that might arise (like: having no gas after the SFM gets handled) or c) play Brainstorm and shuffle away stuff, which you don't need to because your hand is good.
So, play the Mystic and proceed to win if he can't handle it. More realistically, it will resolve but it will either get plowed or you will get thoughseized, which you cannot prevent anyway. After that, find more pressure and wasteland your opponent to make your Spell Pierce better against stuff like Lili and Jace.