SummenSaugen: Thanks for the correction on Null Rod for some reason I was thinking it was a triggered effect. If I was playing against UrLandStill what you are describing would work, but that white splash gave them Swords to Plowshares in place of Lightning Bolt. This is what made even a fast start for me not so good. If they didn't have the white splash I would have probably won every game that I had a quick start. Also, unless they sac the Disk in
desperation to remove a Dreadnaught or Phage, you can bet your ass they are following up with a Standstill. So as soon as you cast your Duress they get three more cards that always seemed to be 1 counter and 1 removal spell. And like I mentioned earlier they have the tools to totaly destroy your mana base, so in most cases you do not have the resources to play protection and bombs post Disk. For example the last game I played this past weekend I had 1 Bayou on turn 8...Stifle hits Fetchlands, Wastelands hit your lands, and Disk hits all your mana dudes. Maybe it just wasn't my day, and I know ten games is not the proper amount of testing, but it really felt like UrwLandStill was the anti-Ninja Mask deck. And to be honest nothing will fix it because it attacks every one of Ninja Mask's strategies on every front. Can you outrace it sometimes and win? Yes. Can you win a hard fought game? Possible but doubtful. Why? Because you do not attack any of their resources, and they constantly attack yours. Therefore, you can only win if you can sneak your combo in when they do not have removal or counters to foil you combo. The only problem is their deck is draw, land, removal (
1/3 mass removal), and counters so it is hard to catch them with their pants down unless you do it very early.
Edited: I have put a lot of thought into this and the best sideboard card to swing game to your favor could possibly to side in 4 Troll Ascetic along with 4 Xantid Swarms to fix the problem. Another option would be Spiritmonger or River Boa, but they are handled by Swords to Plowshares so they are really only strong against UrLandstill, but the could still be used in both matchups.
Troll Ascetic
Color= Green
Type= Creature - Troll Shaman
Cost= 1GG
3/2.
~this~ can't be the target of spells or abilities your opponents control. ;

{G}: Regenerate ~this~.
I would like to see this discusion center more around improving your match-up against decks most people would likely see. Landstill is a bad match-up, but currently it is not that popular of a deck. Until that changes lets not focus on that one match-up.