The most likely first good pet for a starting player Venomancer is the pet egg extracted from the Glacial Walker at level 26. They can be found just at the teleport at Camp Wave Breaker on Barrier Island, coordinates 671 176. It is the fourth best tank in the game, with only the Harpy, Monkey King and Baby Hercules pets, in that order, better. But of course they require a massive investment of gold to acquire, so the Glacial Walker is a very good deal.