Think of it as part of the hunt
Sun Titan Sun Titan, one of the best giants in MTG, is a good piece of mid- to late-game value that constantly gets goodies back from your graveyard, which can include lands, auras, and small creatures
You don't want too many non-zombie cards in the deck and this eats up a bunch of those slots without providing much disruption
Blue Buggy (ST-25) Leader: Buggy (OP09-042) Blue Buggy is all about flooding your board with powerful Cross Guild characters
I think the deck could use some touch-ups that fit into four main categories: better slivers, getting slivers into the graveyard, protection, and lands
As for Sam, Lotal Attendant, he is a 2/4 creature that creates a food token at the beginning of combat on your turn