This is a complex deck that often starts slow, but can quickly grow out of control.  The premise here is to make big creatures with judicious use of +1/+1 counters, rather than by traditional means.  Four different mechanics are employed to this end.  Use your graft creatures for early plays - keep them alive as much as possible since they often offer other benefits, but the Hydropons especially serve more to boost your other monsters than as their own strength.  Phantoms make for splendid blockers as long as you do one of two things: keep them in counters using your other counter'd creatures, or artificially boost their defense (Angelic Shield, Spidersilk Armor, Mirari's Wake) to make them into invincible blockers.  Use them early to keep yourself alive.  The spikes make for excellent counter-nexuses - if you have the option, stack your counters heavily on your spikes so you can move them as you see fit.  And proliferate, proliferate, proliferate.

More detailed notes: There is some small degree of infect here.  Use the Inkmoth Nexus and the Agent to win a poison counter early on, then steadily increase it as the game progresses.  Often times this deck finds itself in a stand-off with other creature decks - not a problem if your proliferate cards are sneaking counters on your opponent every turn.  Stack counters on an Agent to turn him into an unblockable Infect juggernaut, or, conversely, use Distortion Strike on a Spike Soldier and burn off his counters to do major traditional damage.  Stack counters on Tangle Angler to pick off the more threatening creatures your opponent controls, or make him unblockable for the initial infect damage you need.

Additionally, use Venser and Erratic Portal to keep the game going when you're top-decking.  Venser out a Root-Kin to proliferate your creatures for free, or move off the counters from a Spike before bouncing it to get a fresh supply of counters (plus whatever your graft creatures have to offer).  Use Helium Squirter to give your scariest monsters flying, then untap them with the Graftmage after they've done their dirty work.  Feel free to swing with pumped Phantoms - do some damage or kill a blocker at the expense of a mere single counter, easily replaced by Spike or Root-Kin.  Don't forget to Graft your opponent's creatures once the manipulator hits the field, they'll look good on your side under a pile of counters, too.