Incomplete/Budget Standard BUG focused on +1/+1 counters, big bodies and being sneaky sneaky. Great synergy. Fun deck.
Gameplan: Play a few big early creatures, control/stabalize, and go crazy with +1/+1 counters.
Experiment One. Low cmc creature that accumulates counters, pesky to deal with if left alone.
Dreg Mangler: On curve creature with haste. Evolves other creatures and can Scavenge.
Elusive Krasis: 4 toughness stymies early aggro. Accumulates counters. Unblockable is nice.
Vorel: Similar to Elusive krasis, but can evolve it and acts as a mana sink for tricky combat and counter synergy.
Vampire Nighthawk: Flying, Lifelink, Deathtouch. Good against aggro. Good target to place counters on.
Corpsejack: Lynchpin. Amplifies counter synergy. Big on curve creature if nothing else.
Fathom Mage: Incredible target for counters. Incredible card advantage possibility.
Primordial Hydra: Counter generator and threat.
Mutilate: Purely to hate on aggro. If I can hit it early for 3 swamps with my own 4 toughness creature I am happy. Late game situations my creatures grow huge.
Far/Away: Useful card. A common situation is I'll have one or two large creatures and they'll have a greater amount of smaller creatures, and I can't attack because I need to guard my health or unfavorable trades.
Simic Charm: Versatile. Usually for hexproof.
Golgari Charm: Versatile. Combat trick, or to get rid of annoying enchantments. Could also be good in certain matchups.
Bioshift: Excellent combat trick, insane interaction with Corpsejack's effect, and can be used to lessen effects of removal by keeping counters in play.