Muktol

[[Stonehorn Dignitary]] is a classic target for flicker-effects in pauper.

What about some of the Phoenix-creatures? [[Chandra's Phoenix]] or [[Flamewake Phoenix]] could help against "sudden surprises".

[[Valiant Veteran]]
A description would be a nice addition to your decks. This makes it easier on making suggestions and understanding the deck.

[[Blade of Selves]] could be an idea, tough the tokens won't deal commander damage. Another thing that I like to add to a deck when I'm using a commander that I want protected would be [[Swiftfoot Boots]]. [[Darksteel Plate]] could also be used, but is rather expensive, [[Kaldra Compleat]] or [[Indestructibility]] would be a little bit cheaper.

[[Mirror Box]]/ [[Mirror Gallery]]/ [[Sakashima of a Thousand Faces]] would enable you to generate a large number of 3/3 Frogs and slowly drain your opponents of their life.

I added 2 [[Pentad Prism]] instead of 2 basic lands. There where some occasions where I would have been able to cast another proliferate spell with just a little bit more mana, or proliferate and activate [[Festercreep]], tough those situations where rather rare.

I don't have an auto-correction, I'm writing things on a computer in a browser... which checks for spelling, but doesn't change it automatically. These are simple mistakes I didn't see at the time I was writing it.
But yes, auto-correction can be a bitch. The word, or in this case the acronym, I'm having the most problem with would be "DSA" which is always converted into "DAS" (German spelling rules).

[[Sphinx's Tutelage]] could convert the deck from a beatdown to a mill strategy. Big surprise for an opponent on Game 2.

Another option would be [[Zada, Hedron Grinder]] + [[Venerated Rotpriest]] = Instant death. Tough this would need a red splash.

[[Venerated Rotpriest]] + [[Wild Defiance]] = pain

[[Skyhunter Skirmisher]] instead of [[Leonin Skyhunter]?

What about [[Colossus Hammer]]? I would also include something to protect against removal, like [[Darksteel Plate]] for example.

[[Etched Champion]]

Personally I would remove [[Atog]] and [[Paradise Mantle]] and focus more on enchantments. I see some other issues with cards in the deck, but this would be my first step.

As for [[Paradise Mantle]]: A creature equipped with the Mantle works just like a land then, with one bid difference: A creature has summoning sickness, while a land can be tapped the turn you play it.

Graveyard hate is a part of almost any sideboards, some decks even play it mainboard, so yeah, a replacement for [[Myr Servitor]] would be an idea. What about some affinity creatures? [[Frogmite]], [[Myr Enforcer]], [[Steelfin Whale]] (or [[Gearseeker Serpent]] which you already mentioned)?

Personally I would rather try to target a bridge-land with [[Kenku Artificer]]. Anyone in need of an Indestructible 3/3 flyer? Yes please!

[[Sylvok Lifestaff]] vs. [[Bonesplitter]] is a question of aggro vs. midrange, and as this decks looks more like a midrange deck, [[Sylvok Lifestaff]] would fit better here.

The only real thing in terms of mass removal in pauper (in this colour-combination) would be [[Fiery Cannonade]], question is if 2 damage will be enough... which I doubt. If you want to have something to deal singe target damage then [[Orcish Vandal]] or [[Makeshift Munitions]] could be worth a look.

[[Ponder]] could be replaced with [[Thoughtcast]].

Wha about adding a 3rd colour? I'm not really a fan of 3- coloured decks, but I saw what pressure my Naya Metalcraft deck could build up, and it was really fun to play. Any of the remaining colours could add to the decks strategy:
Black [[Glaze Fiend]], [[Vampire's Kiss]], [[Deadly Dispute]], [[Vault Skirge]] (Phyrexian mana!)
White [[Ardent Recruit]], [[Auriok Sunchaser]], [[Court Homunculus]], [[Glint Hawk]], [[Greatsword of Tyr]]
Green [[Carapace Forger]], [[Mirran Mettle]]

[[Experimental Synthesizer]] could be something for the deck as it gives you additional draw, can be searched with [[Trinket Mage]] and can generate you a 2/2 token if you desperately need one.

It would be interesting to get a short summary or hear which cards performed well in those 3 matches and which didn't.

[[Order of the Stars]] is one of my favourite defenders for such decks as it can stall anything that doesn't have trample or is an artifact.
[[Perimeter Captain]] or [[Stalwart Shield-Bearers]] could be an option instead of [[Fortified Rampart]], tough the Captain might be a budget problem.

Yes, I've misread, you're absolutely right. At the moment I'm at home for some days and obviously my brain is going numb. ;-)

[[Skullcage]] doesn't seem to fit the deck for me, with all that discard you will want to keep an opponent on zero cards for most of the game. [[Megrim]] or [[Shrieking Affliction]] could be a replacement for this.
[[Scepter of Fugue]] and [[Nihil Spellbomb]] are just some general suggestions.

Duel Commander seems to use the "normal" commander rules for deck-building, like colour identity... or singleton use:
With the exception of basic lands, no two cards in the deck may have the same English name.

There should be enough wolves/ werewolves to fill up the ranks of the deck. For the support side of your deck keep in mind that you will bee playing against a single opponent, so cards normally effective in commander, like [[Blade of Selves]], won't be as strong in duel commander.

Care to explain what DUAL Commander is? The only thing I could find was something about DUELL Commander, which is basically commander deck focused on 1vs1 instead of multiplayer.