Firespout remains my wepon of choice in 5cStax, with 2 dullpliquants and 2 razormane masticore.
I was testing rolling earthquake (which was too mana intensive) so i decided to go for the G sqplash just for the sideboard.
Last tournament Rolling Earthquake would have won me a match that ended tied with Bant, (i played pyroclasm, which i run as replacement).
Trygon is another issue. Welder + Duplicant?
Razormane is a fine answer for Trygon. Bazaar him into your yard and weld him in during your upkeep. He shoots creatures during the draw step.
Hard to set up, plus sadly I don't have Bazaars and I don't currently run them, BTW welding in a Masticore is my usual play against trygon right now.