SB explanation:  In tournament play I founded that a well-built,
well-played suicide black can take the game before I can get an active
weaver into play.  I added the full set of Elephant Grasses to solve this
problem.  When it's that easy to hose a deck, you might as well do it.
It's like having 10 Weavers in the deck, counting survivals.  The set of
Emerald Charms is there for a similar reason--Bloom is getting hot
locally, and it is advantaged vs. survival (though I at least have
disruption with the ants and surgeon).  Charm is the cheapest enchantment
killer, so it's the best vs. gloom, and whereas I might prefer domains vs.
the occasional humil-prayer, I still have the gaea's and eagle for backup.
The monkeys are there because my strategy vs. Mono-Blue with Disks is to
take out most or all of the survivals as they are useless in multiples and
a blue deck will often leave them alone and just counter the creatures.
Besides I don't like to dump the huge fatties vs. blue; that's one more
spell they have to counter, and you eventually *will* be able to cast that
spirit or verdant vs. them.  Pitching the fatties for a beatdown critter
like the boas just thins a useful card out of your deck.  Originally the
SB also contained Oath of Ghouls (2) for control decks but the resurgence
of Bloom demands the Charms replace them.  The Lobotomies are for the
mirror match and general use, and the second Queen is mainly for the
mirror match as well.  The last slot (currently Disintegrate) is a work in
progress.  It has always been devoted to the mirror match.  Early on it
was Shauku, Endbringer, a living StP I can tutor for, but I found this to
be too situational and when I did get it it was thwarted by recurring
jellyfish.  When I added the Gaea's I replaced it with the
less-situational Cannibalize.  Last night, in a stroke of genius, I
replaced that with Disintegrate, which has excellent flexibility as an
ordinary X-spell (so it can be boarded vs. many slower decks) and can also
provide an alternate victory condition vs. other survivals as the weaver
stalemate drags on and lands accumulate.  But mostly it's there for the
same reason as its predecessors--to remove annoying critters like Coffin
Queen from the game.  Note that without the Gaea's in my deck I would not
have this kind of sideboarding flexibility since I would be unable to
recur anything other than creatures.  With the Gaea's I can recur
Volrath's Stronghold, Recurring Nightmare, Lobotomy, Survival, etc., and
the "disadvantage" of reshuffling my deck is a bonus vs. control and
rarely a liability since I use no deaths (as long as I get the angel out
early if my opponent may be using living death).

The 2 man-o-wars are amazing, and much better than tradewind rider.
Recurring one for the other keeps other death decks off balance and denies
them full use of their mana since they waste time recasting creatures.  If
I don't have a recurring nightmare yet, I can reset the other guy's coffin
queen *twice* rather than once, again keeping my opponent off balance
since he must repeatedly tap most of his mana casting a 1/1.  And they are
great vs. all of the local enchantments in white and black, plus
sarcomancy.

Army ants is the right choice for land kill.  It has 3 main advantages
over the orcish settlers many use:  (1) it can't be nekrataaled, (2) it
doesn't take red mana to activate--an issue in my deck with its unusually
high basic land count, and (3) it frees up your mana for other things.
Plus it's amazing with the hermit druid, and it can occasionally lead to
the god draw of birds/turn 2 army ants vs. slow control, which is game
over if they can never get to 4 mana to wrath/disk.

Finally a quick word about SBing:  No matter how useless they may have
been in game 1, I with few exceptions *never* SB out the cloudchaser and 1
of the 2 humpmonkeys.  It's too easy to get screwed doing this by opposing
SB nuisances (furnace, forsaken wastes), even if you've played the same
opponent before and don't think he has anything.