Since your intent is for casual play I won't go too much into what cards you should be playing in Golgari colors but instead focus on the Beast theme you've got going on and add some fun interactions.
I really like the interaction you already have with the Advocate of the Beast and Corpsejack Menace plus Kalonian Hydra. But I think you need to up the beast count a bit to make it more fun.
Absolutely need the 4 pack of Kalonian Tusker since this is a beast deck, recommend cutting the Accursed Spirit, the Woodborn Behemoth, and either a Giant Spider or a Rootwalla.
Lotleth Troll would also be a happy addition, and also works well with Corpsejack Menace and Kalonian Hydra.
If you have Whip of Erebos the interaction between Lotleth Troll, Kalonian Hydra, and Whip of Erebos is a really fun one to hit, especially if you can manage to have Corpsejack on the board as well.
Since you don't have any value one-drops that you can cast on turn one, Golgari Guildgate is actually a good 4 of in this deck, replace a forest and the 3 Transguild Promenade with 4 of the guildgates.
Example nut draw could play out like:
Turn 1: Golgari Guildgate
Turn 2: Forest, Lotleth Troll
Turn 3: Forest, Kalonian Tusker, Lotleth Troll: Discard Kalonian Hydra for +1/+1, Troll attacks with giant growth for 5 or for 3 and regenerate.
Turn 4: Swamp, Whip of Erebos, Troll and Tusker swing for 6 damage and 6 life gain.
Turn 5: Discard any creatures in your hand to pump Lotleth Troll, use Whip on Kalonian Hydra, swing with everyone Hydra for 8 trample, Troll get's all +1/+1 counters doubled swinging for at least 4 with trample, and Tusker for 3 possibly for the win.
A really fun win-condition if you ask me. Not likely to happen just like that or that fast but later in the game with the Advocate pumping your beasts the Hydra's doubling of counters gets even better.
I'll post a modified version of what I would do with this deck.