Very cool deck my only suggestion would be to add Primordial Hydra because it works so well with Kalonian Hydra . If you would mine check out my deck Counting With Hydras . +1

HydraOoze -- It's easy to suggest adding things, but there's only 60 cards in the deck. What would you take out for Primordial Hydra ? It's not as good as Kalonian Hydra , and I ran out of space to fit it. Swapping in Mistcutter Hydra for Primordial Hydra gave me haste and cheaper casting cost, which has won games for me during playtesting.

Switch Fungal Behemoth for Primordial Hydra .

HydraOoze, that's just wrong.

Fungal Behemoth is a beast, and much faster than Primordial Hydra . If Kalonian Hydra is on the field, then the behemoth is hardcast for 4 CMC and mirrors Kalonian Hydra's power and toughness (minimum 8/8 after the attack). Or you can cast it the turn before for 3 CMC, give Kalonian Hydra a +1/+1 counter before it attacks and doubles, and they both swing that turn as minimum 10/10. If another creature with a +1/+1 counter is on the field, Fungal Behemoth is even more huge. And any +1/+1 counter that's put on Fungal Behemoth (such as from Llanowar Reborn or Oran-Rief, the Vastwood ) both A) keeps it around on its own, and B) is effectively doubled.

In comparison, for 3 CMC, the Primordial Hydra enters as a very-susceptible-to-removal 1/1 and doubles to a mere 2/2 when Kalonian Hydra attacks. For 4 CMC, it enters as a still-very-susceptible-to-removal 2/2 and doubles to a 4/4. And, unlike the Fungal Behemoth, it's got no synergy with any other creature on the field.

Try again?

Spike Feeder + Archangel of Thune = infinite +1/+1 counters for all your creatures along with infinite life.