You'd think that in a tournament with such a low countermagic (and even discard) count, Storm would be able to dominate. Alas, instead of the traditional measures, we have Gaddock Teeg.
Advice
this turned into more of an essay, sorry for Lyco on that key G2 turn:
You should be identifying key parts to the match: your threats, their threats; your answers, his answers; your weaknesses, and his weaknesses. Particularly prominent here were your diverse array of threats, and his shallow pool of answers - you had Teeg forcing him off Ad Nauseam, Past in Flames, and Tendrils, and a Marit Lage combo about to go off. Deathrite was policing the graveyard and adding to your otherwise slow clock, and Scooze was ready to duplicate that role. You'd Thoughtseized him, and knew that he had a Chain of Vapor as an available answer.
Your two
biggest angles of attack here are clearly Teeg and Marit Lage. Scooze and Deathrite are very good, but they don't put anything like the same pressure on him - especially as he looks to be more of an Ad Nauseam storm variant (which we used to call TES), instead of focusing on Past In Flames and the graveyard (ANT). You've caught him in a pincer: either he subjects himself to Gaddock Teeg and has to win with several key cards off the table, or he has no way to stop your angry 20/20 killing him in two turns.
You should therefore concentrate on this pincer and making each side of it as painful for him as you can. Teeg's side is the controlling one, so you should home in on enabling that as best as possible. Like most control situations, the life total doesn't matter as long as they're not capable of
doing anything. You can peck away at them as slow as you like (though Deathrite, Scooze, and Teeg all together would have been a decently fast clock). Marit Lage was your damage side, and that involves hitting him for 20 outright, so the life total still doesn't matter.
The point of all this is that I would have changed that turn from this:
Dark Depths
Scrubland, Deathrite: Exile Thoughtseize for two
Forest, Wasteland: cast Scooze
Attack with Dryad Arbor + Teeg
to this:
Dark Depths
Dryad Arbor, Forest: cast Scooze
Attack with Teeg.
This means that:
Deathrite is still available, with black mana, to take spell cards out of his yard (and you should always be exiling stuff from theirs, not yours, except under particular cirumstances which mostly involve removing Tarmogoyf card types as you were doing against me. This is especially true when you're playing Storm).
Wasteland is still up to harass his poor mana, one of the weaknesses he's clearly suffering under. Yes, if he goes off this coming turn, he'll still get mana out of a non-basic drop, but he'll have to choose
immediately when you get priority. There's value in him having to decide on U or R out of a Volcanic, say, without knowing all the cards he's going to draw. Even if he's setting up this turn to go off on the next, when Thespian's Stage demonstrates he's about to die, then you can still restrict his options with the Wasteland threat.
To keep up the Wasteland and the Scrubland, we've had to use a Forest and the Dryad Arbor. This, however, isn't likely to be very relevant. That single point of Dryad Arbor means very little, when you think back to your pincers - on the one hand, you can go as slow as you like if you're controlling him; on the other, you're killing him with Marit Lage so him being at 11 instead of 12 is of no value. We've lost the use of green mana, but what's Deathrite going to do with it? He doesn't play creatures, and yours aren't likely to die against a storm deck - and if they do, somehow, how likely is two life extra to win you the game anyway?
(Alternative option, focusing more on yard control than mana denial: use the Wasteland and Forest to cast Scooze, then hold up the Arbor for a source of G for Scooze so you can exile two things. Either way, you want to use the Arbor for mana, not damage).
I mean ... you won anyway, so this might all be of limited relevance, but it was an interesting scenario with some varied options, which I think illustrates some vital Magic-playing principles.