I would try to stay away from defenders if all possible.
Wild beastmaster 
needs you to have plenty of attacking creatures and plan A (make a bunch of saprolings with
korozda guildmage 
and scavenge the creatures) is a situation that you can't always count on. Even if you have 4 guildmage and 4 beastmaster and 4
dreg mangler 
(probably the best scavenge option for this scenerio) you would need a near perfect draw to pull off something like Turn 1
arbor elf 
, turn 2
dreg mangler , turn 3
korozda guildmage , turn 4
wild beastmaster 
, turn 5 sac dreg mangler get 3 saprolings, turn 6 scavenge then swing for 30.
I'm not saying to scrap the idea. The good news is that even though it's a slow process these are all things you're going to want to do anyway. Turn 2
dreg mangler is a pretty awesome threat on it's own and
korozda guildmage has a great board presence allowing you to get value out of any targetted removal they try to point at your creatures. The one card that really needs support in this decklist to make it work is
wild beastmaster which is pretty bad unless she's put in the right situation (without any pumps she's a 3 man 1/1 with battle cry essentially).
Costs to scavenge 0 mana for 1/1, 3 mana for 2/2 (on less than efficient creatures), 4 mana for 3/3 (on a 6 mana flier), 5 mana for 3/3 (dreg mangler, good card), 6 mana 5/5 (another good card
deadbridge goliath 
. So far the decklist would look something like
4 -
arbor elf 4 -
slitherhead 
(not really a great option but I guess not bad for a beastmaster decklist)
4 -
korozda guildmage 4 -
dreg mangler 4 -
deadbridge goliath 4 -
wild beastmaster 1 -
golgari decoy 
(not big on him but he can help to push through damage since wild beastmaster doesn't provide trample)
That is already 24 creatures which is basically what you want for a decklist like this. You can mess with the numbers a bit if you want
strangleroot geist 
or some other efficient beaters. Maybe something that gives you multiple bodies like
spider spawning 
or
moan of the unhallowed 
, or Garruk if you have him.
Beyond that you might want some removal like
golgari charm 
(though less good due to all the 1/1 creatures you're playing but there is some versatility), or some
grisly salvage 
, or some pump like
rancor 
in case you don't have the mana to scavenge.
I hope I'm not coming off mean, there is just so many different directions you could go with this deck. You could go beatdown with
dryad militant 
,
strangleroot geist , and
rakdos cackler 
to make
wild beastmaster a big finisher with some cheap pump spells like
rancor or
giant growth 
but that would exclude the scavenge theme which is slower to set up. Also you could go more of a "rock" style deck which is slower and could make good use of the scavenge mechanic but wouldn't really use a card like
wild beastmaster all that much. The cards seem to have good synergy guildmage, beastmaster, scavenge but the decklist plays out so slowly I fear that it won't be fun even for casual games..... I guess it depends on your group. How much mass removal do you guys play?
